1. Definition of continental margin

An important point often overlooked is that the Geneva Convention on the Continental Shelf (Geneva Convention)Footnote ⁵⁶ did not define the continental margin. This omission was the principal cause of the disarray that followed the unfortunate inclusion of the alternative definitions of the continental shelf under Article 1 of the Geneva Convention.Footnote ⁵⁷ The omission of any reference to the continental margin created significant ambiguity over whether geologyFootnote ⁵⁸ could constrain an otherwise infinite seaward extent of entitlement according to the exploitability criterion.Footnote ⁵⁹ If it could, the exploitability criterion would have geological boundaries, and thereby imply an inherent constraint on the seaward extent of entitlement pursuant to this criterion.Footnote ⁶⁰

After lengthy negotiations, one of the significant achievements of the Conference was the consensus around the definition of the notion of continental margin.Footnote ⁶¹ The definition of the continental margin contained in Article 76(3) of UNCLOS is based on three distinct features: (i) the shelf, (ii) the slope and (iii) the rise; all of which constitutes the submerged prolongation of the land mass of the relevant coastal State. These are morphological features, which may be linked to any land mass. It was an apparently deliberate choice to exclude any reference to crustal structure as a composite element of the continental margin.Footnote ⁶² Accordingly, the definition of the continental margin in paragraph 3 is a juridical definition. In this regard, it is important to have in mind that paragraph 4 relies on some of the morphological composite elements that constitute the continental margin, as defined in paragraph 3. Paragraph 4 is an operative paragraph that determines the outer edge of the continental margin and operates notwithstanding the crustal structure of the seabed and subsoil.

During the Conference, a critical question was whether elongated ridge-like features were capable of generating entitlements beyond the 200 nm distance line from the baselines. In the first revision of the Informal Composite Negotiating Text, the precursor of Article 76(3) did not include any reference to oceanic ridges. Yet, the paragraph was followed with a footnote reference which provided that ‘general understanding had been reached to the effect that on the question of underwater oceanic ridges there will be additional discussion and that a mutually acceptable formulation to be included in article 76 will be drawn up’.Footnote ⁶³ The matter was further discussed during the eighth session of the Conference. Several proposals sought to limit the outer limits of the continental shelf to a 350 nm distance line from the baselines where the seafloor high shared morphological characteristics of a ridge-like feature.Footnote ⁶⁴ The compromise crystallized during the ninth session. This not only led to the current formulation of paragraph 3 but also to the inclusion of a paragraph 5 bis of Article 76.Footnote ⁶⁵ The notion of ‘underwater oceanic ridges’, to which the first revision of the Informal Composite Negotiating Text referred, was bifurcated into two separate categories. On the one hand, the result was a reference to ‘the deep ocean floor with its oceanic ridges’ in the second sentence in paragraph 3. On the other hand, the term ‘submarine ridges’ appeared in the new paragraph 6 of Article 76.Footnote ⁶⁶ Neither paragraph refers explicitly to the crustal nature of these features, but the retention of the term ‘oceanic ridges’ in the second sentence of paragraph 3 of Article 76Footnote ⁶⁷ could suggest that crustal structure could matter for determining which features are parts of the continental margin. However, the second sentence of paragraph 3 in conjunction with the first sentence of paragraph 6 are symptomatic of the painstaking compromises that result in treaty provisions becoming ‘disagreement[s] reduced to writing’.Footnote ⁶⁸ As the CLCS Guidelines point out, paragraphs 3 and 6 of Article 76 ‘may create some difficulties in defining ridges for which the criterion of 350 nm in paragraph 6 may apply on the basis of the origin of the ridges and their composition’.Footnote ⁶⁹ While the records of the Conference meetings can set out the compromise that was reached among the participants, they are unable to shed light on what it meant, as the compromises were reached in closed groups.Footnote ⁷⁰ Therefore, they are inapposite as supplementary treaty interpretative means.Footnote ⁷¹ The legislative history of paragraphs 3 and 6 are interrelated but it appears clear from the ordinary meaning of the first sentence of paragraph 6 that the restriction on submarine ridgesFootnote ⁷² is not an exception to paragraph 3 of Article 76 but an exception to Article 76(5) only. Thus, while it is generally accepted that customary treaty interpretation principles provide that an exception to a rule should not lend itself to an extensive interpretation,Footnote ⁷³ the first sentence of paragraph 6 is not an exception to paragraph 3 of Article 76. Accordingly, the above-mentioned customary treaty interpretation principle cannot be construed to support that an argument that ‘submarine ridges’ in paragraph 6 of Article 76 is to be given a restrictive meaning by referring to the idea of ‘oceanic ridges’Footnote ⁷⁴ in the second sentence of paragraph 3 of Article 76.

2. The general rule contained in UNCLOS

The second sentence of UNCLOS's definition of the continental margin, contained in Article 76(3), provides that the margin ‘does not include the deep ocean floor with its oceanic ridges or the subsoil thereof’.Footnote ⁷⁵ At first sight, it would appear that this refers to the crustal structure, yet as mentioned earlier the drafters deliberately decided to exclude crustal structure as a constitutive criterion of the continental margin under paragraph 3 of Article 76.Footnote ⁷⁶ This is also clearly reflected in the ITLOS decision in the Bay of Bengal case in which it emphasized that it ‘cannot accept Bangladesh's contention that, by reason of the significant geological discontinuity dividing the Burma plate from the Indian plate, Myanmar is not entitled to a continental shelf beyond 200 [nm]’.Footnote ⁷⁷ This does not mean that geological discontinuities are immaterial for the purpose of attributing an ordinary meaning to the notion ‘oceanic ridges’ in the second sentence of paragraph 3, by contrast to the notion of ‘submarine ridges’ in paragraph 6,Footnote ⁷⁸ and which are mutually exclusive. One such question is whether the presence of a continental-oceanic transition (COT) on a ridge makes such a seafloor high a part of the deep ocean floor with its oceanic ridges and therefore part of the Area.

Answering this question in the abstract would, however, disregard paragraph 4(b) of Article 76, which provides that ‘[i]n the absence of evidence to the contrary, the foot of the continental slope shall be determined as the point of maximum change in the gradient at its base’.Footnote ⁷⁹ The latter part of this provision provides a morphological and bathymetric formula to identify the maximum change in the gradient at which the foot of the continental slope is determined. The formula constitutes ‘a general rule’.Footnote ⁸⁰ The determination of such foot of slope points is preceded by the identification of a common envelope of the base of slope, as paragraph 4(b) of Article 76 states that the foot of the slope is to be determined ‘at [the] base’Footnote ⁸¹ of the slope. Thus the base of slope within which the foot of slope is determined can be identified according to a mere morphological and bathymetric analysis, where it may be ‘clearly determined’Footnote ⁸² on such evidence alone. Geological and geophysical data may supplement the morphological and bathymetric data to identify the base of slope. The latter are only required when the morphologic and bathymetric data are insufficient to determine the base of slope and its associated foot of slope points. Consequently, as the base of slope may be determined exclusively according to a morphological and bathymetric analysis, there is no requirement to determine whether a COT is located on a ridge-like feature.Footnote ⁸³ This follows directly from the first sentence of Article 76(3), which as mentioned earlier not only omits any reference to crustal structure as a composite element of the continental margin but relies exclusively on morphological features in its definition. As has been observed elsewhere, ‘when paragraph 4 [of Article 76] refers to the continental slope and the foot of the continental slope, it is with reference to the continental margin in the sense of the [UNCLOS]. The consequence is that any kind of landmass (irrespective of crustal type) may generate a continental margin in the sense of [UNCLOS] that can be delineated in accordance with paragraph 4 of article 76’.Footnote ⁸⁴ Given this background, it may be concluded that the crustal structure of the seabed has no constitutive role in determining the continental margin where the base of slope may be identified pursuant to a morphological and bathymetric analysis alone.

Geology and geophysics may nevertheless have importance for the purposes of determining the continental margin where the ‘evidence to the contrary’Footnote ⁸⁵ rule is invoked. The evidence to the contrary rule provides an alternative formula for determining the foot of slope by allowing for geological evidence to substitute for the general rule in cases where morphological and bathymetric data do not provide a sufficiently accurate foot of slope point.Footnote ⁸⁶ The Guidelines provide a non-exhaustive list of geological parameters to identify the foot of slope that are determined according to the evidence to the contrary rule. These parameters depend on the nature of the continental margins.Footnote ⁸⁷ It appears that the landward limit of the COT ‘might be considered by the [CLCS] as an equivalent of the foot of the continental slope in the context of paragraph 4’Footnote ⁸⁸ in so far as concerns some continental margins.Footnote ⁸⁹ However, as has been rightly observed by the CLCS, the evidence to the contrary rule has ‘the character of an exception’Footnote ⁹⁰ to the general rule. Thus, it is subsidiary in nature and does not alter the general rule for determining whether a feature is part of the continental margin based on morphology and bathymetry. From this background it can be concluded that any feature which is landward of the foot of slope is part of the continental margin, notwithstanding geological settings.

This is reflected in numerous recommendations of the CLCS and in the so-called test of appurtenance, applied by the CLCS.Footnote ⁹¹ In its recommendations to Barbados, the CLCS failed completely to analyse the geological setting to determine whether the seafloor highs in question were capable of generating entitlement beyond 200 nm. It limited itself to observing that ‘[f]rom a morphological point of view, the seabed features in the vicinity of the Barbados submerged prolongation … can be considered as natural prolongations of the Barbados landmass’.Footnote ⁹² In its recommendations to New Zealand the CLCS determined on a morphological basis that the Fantail Terrace was part of the Three King Ridge and as such it was acceptable for it to generate outer edge points of the continental margin pursuant to either of the formulae under Article 76(4)(a) of UNCLOS. The CLCS held that ‘the location of the base of the continental slope, i.e. the transition from the slope to the deep ocean floor of the South Fiji Basin is identified on a morphological basis, recognising that the Fantail Terrace is an integral part of the Three King Ridge System. Accordingly, the eastern flank of the Three King Ridge may be readily delineated by its foot of the continental slope envelope’.Footnote ⁹³ Further, in its recommendations to Japan, the CLCS refused on the basis of an entirely morphological analysis to accept that the Mogi Seamount Region was part of the continental margin of Japan: ‘In the Mogi Seamount Region the saddle area is not significant enough to create morphological continuity between the Mogi Seamount and the Izu-Ogasawara Arc. Therefore the Subcommission agreed that the Mogi Seamount is not regarded as a part of the continental margin of Japan in the sense of Article 76.’Footnote ⁹⁴ Indeed, among the 26 recommendations that the CLCS has made thus far, the demonstration of the submerged prolongation of the land mass beyond 200 nm is not, except in one case, made contingent upon the demonstration of geological links with the land mass.

In the recommendations to the Cook Islands, the CLCS seeks blatantly to reverse its understanding of Article 76(3). It seeks to introduce a geological requirement in addition to the morphological and bathymetric requirements for the purposes of demonstrating that the submerged prolongation of the land mass extends beyond the 200 nm distance line. The CLCS observed, inter alia, that the ‘key questions relating to natural prolongation’ includes whether ‘natural prolongation [can] be ensured morphologically and geologically from the islands to the base of the continental slope proposed in the Submission’.Footnote ⁹⁵ Thus, despite admitting morphological continuity with the land mass, the CLCS refused to accept that parts of relevant seafloor highs were integral parts of the continental margin because of the failure to demonstrate geological continuity. The CLCS held that ‘only those seafloor highs for which a morphological and geological connection to the High Plateau could be clearly demonstrated should be considered part of the continental margin of the Cook Islands’.Footnote ⁹⁶ It appears to rely on the notion ‘natural prolongation’, which relates to paragraph 1 of Article 76, to add the supplementary geological requirements in the application of paragraph 3 of Article 76. According to the CLCS, ‘due to the lack of conclusive geological and geophysical data and information, and the resulting uncertainties in the tectonic hypotheses, the Subcommission found that there was limited geological and geophysical support to substantiate the natural prolongation of the landmass beyond the High Plateau’.Footnote ⁹⁷ The above clearly stands in contrast to the firm view expressed by ITLOS in the Bay of Bengal case according to which it ‘finds it difficult to accept that natural prolongation referred to in Article 76, paragraph 1, constitutes a separate and independent criterion a coastal State must satisfy in order to be entitled a continental shelf beyond 200 [nm]’.Footnote ⁹⁸ This arises as the CLCS appears to attach criteria to paragraph 1 of Article 76 with a view to determining whether entitlement to the continental shelf extends beyond the 200 nm distance line notwithstanding the subsequent provisions in Article 76 of UNCLOS. Thus, when holding that ‘there was limited geological and geophysical support to substantiate the natural prolongation of the landmass’Footnote ⁹⁹ of the Cook Islands it appears that the CLCS is attributing a separate and autonomous meaning to the notion ‘natural prolongation’ in Article 76(1) of UNCLOS. Yet, as stressed by ITLOS in the Bay of Bengal case the concept natural prolongation ‘should be understood in light of the subsequent provisions … Entitlement to a continental shelf beyond 200 [nm] should thus be determined by reference to the outer edge of the continental margin, to be ascertained in accordance with article 76, paragraph 4.’Footnote ¹⁰⁰

The conclusions of the CLCS with regard to the submission of the Cook Islands may potentially impact the understanding of whether some parts of the Central Arctic Ocean can rightly be claimed to constitute natural prolongations of the land terrirtories of the respective coastal State(s). Yet, it is difficult to draw firm conclusions from this single document, not least because it is quite clear that the CLCS has come to diametrically opposite conclusions when considering other submissions. In any event, and leaving aside the fact that variable understandings of Article 76 may prejudice the careful balancing which resulted in Article 76 and Annex II to UNCLOS, given that the mandate of the CLCS is to make recommendations in accordance with Article 76, the function of the CLCS, to the same extent as that of international courts and arbitral tribunals, ‘is to make use of geology only so far as required for the application of international law’.Footnote ¹⁰¹

1. The refusal to exclude seafloor highs on geological grounds

All coastal States in the Central Arctic Ocean transmitted diplomatic notes upon the transmission of the submission of Russia to the CLCS on 20 December 2001.Footnote ¹⁰² Yet, it was the diplomatic note of the United States to the United Nations Under-Secretary-General for Legal Affairs on 18 March 2002, in response to the submission of Russia, which was the most notable.Footnote ¹⁰³ It questioned the basis of the methodologies used by Russia with regard to its claimed entitlement to an outer continental shelf in the Central Arctic Ocean. Some of the issues raised by the United States are relevant to whether ridge-like features in the Central Arctic Ocean are composite elements of the continental margins of the coastal States whose coasts abut the Central Arctic Ocean.

It appears from publicly available information that Russia considers the Alpha-Mendeleev Ridge System to be a submarine elevation that is a natural component of its continental margin. The United States diplomatic note appeared to obfuscate the distinction between submarine elevations that are natural components of the continental margin on the one hand with submarine ridges on the other when contending that the Alpha-Mendeleev Ridge System ‘is not part of any State's continental shelf’.Footnote ¹⁰⁴ As explained above the determination of continental margins under Article 76(3) is essentially a morphological and bathymetric exercise. The identification of a common envelope of the slope, within which the foot of slope is established, determines which seafloor highs belong to the continental margin and, by implication, also determines which seafloor highs that are part of the deep ocean floor and its oceanic ridges. This methodology is carefully described under the test of appurtenance in the Guidelines.Footnote ¹⁰⁵

From this background it can be concluded that it is only if the Alpha-Mendeleev Ridge System cannot be included within such a common and continuous envelope of the base of slope that this seafloor high is not to be considered to constitute the submerged prolongation of the land mass of the relevant coastal State. In support of its argument, the United States diplomatic note made an analogous conclusion with regard to the Iceland-Faroe Ridge. It provides that ‘[t]he Alpha-Mendeleev Ridge is identical in origin to the Iceland-Faroe Ridge, an oceanic ridge of volcanic origin of similar thickness and morphology … It is similar in magnetic character to the magnetic anomaly field generated by the oceanic Iceland-Faroe Ridge.’.Footnote ¹⁰⁶ On these geological and geophysical grounds, the United States concluded that ‘[t]he Alpha-Mendeleev Ridge is not, therefore, a submerged prolongation of the land mass of Russia’.Footnote ¹⁰⁷ A fortiori, it would follow on that basis that neither the Faroe-Iceland Ridge, nor the Ægir Ridge, which extends in a seaward direction from the Faroe-Iceland Ridge would, because of their volcanic origin, be capable of being classified as integral parts of the continental margin of the Faroe Islands. The above a fortiori conclusion would appear relevant irrespective of whether or not a common envelope could be identified around a base of slope region in accordance with the general rule under Article 76(4)(b), ie in which only bathymetry and morphology are constitutive elements.

In its recommendations to Denmark, however, the CLCS recognized explicitly that the Faroe-Iceland Ridge, and the Ægir Ridge, notwithstanding their geological discontinuity with the land mass of the Faroe Islands, are integral parts of the continental margin as a common and continuous envelope of the base of slope links these seafloor highs with the land mass of the Faroe Islands. On this basis the seafloor highs are considered as being able to generate entitlement to outer continental shelf. The CLCS referred to the position taken by Denmark, according to which the Ægir Ridge is a submarine ridge within the meaning of the first sentence of Article 76(6). It noted that according to Denmark: ‘since the Ægir Ridge is morphologically continuous with the continental margin north of the Faroe Islands … yet is an extinct seafloor spreading ridge that is geologically different from the landmass of the Faroe Islands, it is a submarine ridge in the meaning of article 76, paragraph 6, of the Convention’.Footnote ¹⁰⁸ The CLCS then observed that ‘it agreed with th[e] view’Footnote ¹⁰⁹ that the Faroe-Iceland Ridge and its northern extension, the Ægir Ridge, are composite elements of the northern continental margin of the Faroe Islands on the sole ground of morphology, notwithstanding fundamental geological differences with the land mass.

It follows that the data and other documentation presented by Denmark supporting the claim that the Faroe-Iceland Ridge and the Ægir Ridge were composite elements of the continental margin within the meaning of Article 76(3) were approved by the CLCS, notwithstanding their considerable geological discontinuity with the land mass of the Faroe Islands. A fortiori, the fact that ‘the Alpha-Mendeleev Ridge System is underlain by unusually homogeneous crust with moderate to high seismic velocities that resemble those measured in the oceanic Iceland-Faroe Ridge’Footnote ¹¹⁰ cannot constitute grounds for excluding the Alpha-Mendeleev Ridge System from forming part of the continental margin of the relevant coastal States to the Central Arctic Ocean. On the contrary, it is the location of the continuous base of continental slope region that determines whether the Alpha-Mendeleev Ridge System or any other seafloor high in the Central Arctic Ocean is a part of the coastal States continental margins.

2. A distinct morphological feature

The CLCS recommendations to the United Kingdom in relation to Ascension Island are instructive in relation to the question whether morphological ridge-like features, with different crusts than those of the land mass whose submerged prolongation they represent, are integral parts of the continental margin of the relevant coastal States in the Central Arctic Ocean. As mentioned earlier, the Gakkel Ridge, an active oceanic spreading ridge, is such a feature. In its recommendations to the United Kingdom, the CLCS observed that ‘the true oceanic features of the seafloor occur seaward of the continental margin and include both the ocean basin floor and [mid-ocean ridge] zones. This categorisation is reflected in article 76, paragraph 3, of the Convention, which states that the continental margin “… does not include the deep ocean floor with its oceanic ridges”.’Footnote ¹¹¹

It would be erroneous to conclude from this that mid-ocean ridges are unable to constitute integral parts of a continental margin. This can arise where the data demonstrates that a seafloor high is morphologically continuous with the land mass, since such a seafloor high cannot be ‘seaward of the continental margin’.Footnote ¹¹² In order to bolster its position that Ascension Island was entitled to an outer continental shelf, the United Kingdom referred to point 7.2.8Footnote ¹¹³ of the GuidelinesFootnote ¹¹⁴ and, it can be assumed, by so doing sought to distinguish this situation from active spreading ridges, which have no islands on them. It appears also that the United Kingdom sought to attach a secondary role to morphology and bathymetry for the purposes of identifying the base of the continental slope. The United Kingdom held that it does

It would appear, accordingly, that the United Kingdom sought to reverse the order of the general rule by seeking to attribute a secondary role to morphology. The CLCS refused to accept the approach of the United Kingdom. The CLCS observed further that ‘islands surmounting discrete morphological features (including ridges) rising from this deep ocean floor are entitled to a “continental margin” and “continental shelf”’.Footnote ¹¹⁶ In the case of ridges surmounted by islands the question arises as to which parts of such ridges are of the deep ocean floor, and which parts constitute the continental margin. The CLCS stressed that the guiding criterion for including seafloor highs in the continental margin of a land mass ‘depends on the location of the base and the [foot of slope] within the submerged prolongation of those islands. Therefore, the [foot of slope] must be situated more than 140 nm from the territorial sea baselines in order to establish an outer edge of continental margin beyond 200 nm using the 60 nm distance formula’.Footnote ¹¹⁷ The CLCS observed that in order for this to be the case for a small oceanic island like the Ascension, ‘it would have to surmount a discrete seafloor high, that itself rises above the average “ruggedness” of the deep ocean floor … In the view of the Commission, the data submitted by the United Kingdom does not demonstrate such a situation’.Footnote ¹¹⁸ Thus, the CLCS refused to accept the geological arguments by which the United Kingdom sought to extend the base of the continental slope further seaward.Footnote ¹¹⁹

The main reason for not accepting the claimed entitlement of the United Kingdom from Ascension Island relates exclusively to morphology. In the words of the CLCS, ‘the existence of a continental slope requires the existence of a distinct morphological feature rising from the level of the continental rise or the deep ocean floor up to the continental shelf of the land mass of the coastal state’.Footnote ¹²⁰ From this background it can be concluded that the recommendations of the CLCS to the United Kingdom, together with the recommendations relating to the Faroe-Iceland Ridge and the Ægir Ridge, constitute benchmarks on the role that the CLCS attaches to morphology for determining the base of slope region.Footnote ¹²¹ This is an important exercise because it determines whether a seafloor high is part of the continental margin or whether it belongs to the deep ocean floor and its oceanic ridges. The prominent role of morphology and bathymetry has particular relevance for the discussion whether the Gakkel Ridge, an active oceanic spreading ridge, can constitute part of the continental margin of relevant coastal States to the Central Arctic Ocean.

3. Gakkel Ridge

The partial submission by Denmark/Greenland, with regard to the northern continental shelf of Greenland,Footnote ¹²² included within its continental margin an active mid-ocean spreading ridge that runs from the Lena Trough in the Fram Strait to the Laptev shelf of Russia. This elongated narrow seafloor high is denominated the Gakkel Ridge. It is considered the northern prolongation of the Mid-Atlantic Ridge, and connects the Eurasian Basin and the North Atlantic. Due to its geological origin and its nature as an active oceanic spreading ridge with limited geological affinity with the neighbouring land masses, it has been considered a classic example of a seafloor high that belongs to the ‘deep ocean floor with its oceanic ridges’.Footnote ¹²³ A former member of the CLCS has noted that ‘[t]he Gakkel Ridge … is an active ocean spreading ridge that does not seem to connect with any of the continental margins’.Footnote ¹²⁴ Elsewhere, it has been argued that ‘consensus has been reached’ that the Gakkel Ridge is an oceanic ridge within the meaning of Article 76(3) of UNCLOS and therefore not eligible to generate entitlement to continental shelf beyond 200 nm from the baselines.Footnote ¹²⁵ It has also been observed that only two areas of seabed on the Central Arctic Ocean are beyond national jurisdiction, one of which is the Gakkel Ridge, which ‘cannot be included in the continental margin as defined in article 76’.Footnote ¹²⁶ These observations seem to assume that geological factors prevent the Gakkel Ridge from being considered a ‘submerged prolongation of the land mass’Footnote ¹²⁷ of the relevant coastal States abutting the Central Arctic Ocean. Yet, the overwhelming practice of the CLCS rightly indicates unambiguously that the general rule is that geology has no constitutive role for identifying the continental margin. The question is, though, whether the same premise applies to active oceanic spreading ridges, which are held to be the submerged prolongation of a land mass whose crustal structure is continental.Footnote ¹²⁸

The Guidelines provide that ‘[s]ome ridges (including active spreading ridges) may have islands on them. In such cases it would be difficult to consider that those parts of the ridge belong to the deep ocean floor’.Footnote ¹²⁹ One could argue a contrario that the provision above also means that if there are no islands on an active oceanic spreading ridge, it may be difficult to include such seafloor highs within the continental margin, as defined in Article 76(3) of UNCLOS. Yet that understanding would hardly be reconcilable with the ordinary meaning of paragraph 4(b) of Article 76. The latter provision provides a general rule pursuant to which the base of slope is identified according to morphologic and bathymetric data, ie geology has no constitutive role for determining the continental margin. To argue the contrary would also neglect the fact that the Ægir Ridge, while not being an active oceanic spreading ridge, but an extinct oceanic spreading ridge, was considered a submerged prolongation of the land mass of the Faroe Islands—despite the absence of any islands sitting upon the ridge. Furthermore, the CLCS noted that the Ægir Ridge was not only an extinct oceanic ridge but also that it had ‘created oceanic seafloor beneath the Northern Deep as well as the Faroe-Iceland Ridge’.Footnote ¹³⁰ As mentioned earlier, the CLCS agreed with Denmark's understanding that the Ægir Ridge is an integral part of the continental margin of the Faroe Islands, notwithstanding the Ægir Ridge being an extinct oceanic seafloor spreading ridge from which there is limited geological affinity with the land mass of the Faroe Islands. Accordingly, it appears that if the general rule under Article 76(4)(b) is applied,Footnote ¹³¹ geology has no constitutive role to determine whether the Gakkel Ridge, or parts thereof, may be considered an integral part of the northern continental margin of Greenland. This determination is instead contingent upon the demonstration of morphological and bathymetric continuity for the purpose of the geomorphological analysisFootnote ¹³² under point 5.2.1 of the Guidelines.Footnote ¹³³

In light of the CLCS’ understanding of the nature of the Ægir Ridge in relation to Article 76, it appears that the inclusion of any seafloor high in the Central Arctic Ocean within the continental margin is principally a matter of morphology and bathymetry. The quintessential exercise relates to determining ‘a distinct morphological feature rising from the level of the continental rise or the deep ocean floor up to the continental shelf of the land mass of the coastal state’.Footnote ¹³⁴ Geology has only a secondary role in this regard. Thus, provided the geomorphological analysisFootnote ¹³⁵ demonstrates that the Gakkel Ridge is morphologically continuous with the land mass of Greenland, it appears reasonable to assert that this seafloor high is an integral part of the continental margin of Greenland notwithstanding it being an active oceanic spreading ridge which does not share geological affinity with the land mass of Greenland. The assertion that the Gakkel Ridge can be included in the continental margin of the relevant coastal State(s) solely on the basis of morphologic and bathymetric criteria does not, however, accord with the recommendations of the CLCS to the Cook Islands. In those recommendations the CLCS also required the demonstration of geologic continuity between any seafloor high and the relevant land mass of the coastal State in order for it to constitute a part of a continental margin within the meaning of Article 76(3). However, and has already been noted, this not only stands in contrast to the Guidelines and numerous previous recommendations of the CLCS, but also blatantly challenges the interpretation of Article 76 by ITLOS in the Bay of Bengal case.

In any event, it is clear that the Gakkel Ridge cannot constitute a submarine elevation that is a natural component of the continental margin. It shall be demonstrated below that in order for any seafloor high to constitute a submarine elevation that is a natural component of the continental margin, and thus susceptible to the depth constraint, the submitting coastal State must demonstrate geological affinity with the relevant land mass.

1. The meaning of submarine elevations that are natural components of the continental margin

The concept of ‘submarine elevations that are natural components of the continental margin’ in the second sentence of Article 76(6) is distinctive in many regards. This notion has a singular legislative history and provides the context for the term ‘submarine ridge’ in the first sentence of paragraph 6.Footnote ¹³⁶ The latter was included as a safeguard for those States that feared that in the absence of a reference to a particular crustal type Article 76(3) would result in creeping jurisdiction on mid-Atlantic ridges.Footnote ¹³⁷ The inclusion of the notion ‘submarine ridges’ in the first sentence of paragraph 6, and the associated rule thereunder, ensured that ‘on submarine ridges, the outer limit of the continental shelf shall not exceed 350 [nm]’.Footnote ¹³⁸ This means that submarine ridges are not subject to the alternative depth constraint, whilst is applicable, in addition to the 350 nm distance constraint, to submarine elevations that are natural components of the continental margin. The inclusion of the second sentence in Article 76(6) was also a safeguard for those States with broad continental margins, ensuring that their entitlement could go beyond the 350 nm distance constraint line when the outer edge of the continental margin stems from submarine elevations that are natural components of the continental margin. While the first sentence of Article 76(6) is an exception to paragraph 5, which provides that the outer limits of the continental shelf shall not exceed either the distance or the depth constraints, it is clear that the second sentence of Article 76(6) is not an exception to the first sentence of paragraph 6. Thus, where it is established that the outer edge of the continental margin does not exceed the 350 nm distance line, and where the depth constraint provides a limit that is further landward than the distance constraint, there is no requirement to classify the relevant seafloor highs.Footnote ¹³⁹ This arises as only the first sentence of paragraph 6 is an exception to Article 76(5).

The second sentence of Article 76(6) includes a non-exhaustive list of features that constitute natural components of the continental margin. The outer edge of the continental margin that stems from such seafloor highs may be delineated in accordance with the second sentence of paragraph 6 and therefore go further seaward than 350 nm from the baselines.Footnote ¹⁴⁰ Given its non-exhaustive nature, this provision provides little guidance concerning which seafloor highs lack such characteristics. It is observed in the Training Manual that ‘[a]lthough these morphological features are commonly associated with the continental margin, they are not diagnostic of the margin. So there must be additional criteria to qualify them as natural components of the continental margin and to distinguish them from the category of submarine ridges.’Footnote ¹⁴¹ The above appears also in the records from the Conference.Footnote ¹⁴² Commentators have observed that if ‘the reference to “natural component” in the second sentence of paragraph 6 is to have a substantive meaning distinct from that of “natural prolongation” in paragraph 3 of Article, it must be translated into a geological requirement. Otherwise, “natural component” would appear as somewhat of a hollow, tautological expression.’Footnote ¹⁴³ The Training Manual states that ‘to qualify as a natural component of the continental margin, an elevation will have to be in geological continuity with the margin along its full extent, i.e. it has to share the geological characteristics and origin of the landmass of the coastal State’.Footnote ¹⁴⁴ Two former members of the CLCS have also observed that ‘the main diagnostic characteristic of a seafloor high that is a natural component of the continental margin is its geological continuity, throughout its entire extent, with the landmass of the coastal State’.Footnote ¹⁴⁵ This approach also appears in the views of other authors, who emphasize that ‘the term “natural components of the continental margin” must imply a higher standard than natural prolongation with respect to the connection between seafloor highs and the continental margin’.Footnote ¹⁴⁶ Thus, according to this understanding, in order for a seafloor high to constitute a submarine elevation that is a natural component of the continental margin it must share geological characteristics with the land mass from which the seafloor high is a submerged prolongation.Footnote ¹⁴⁷ It seems clear that this is not reflected in the reasoning of ITLOS when it dismisses the role of geology for the purpose of demonstrating entitlement to the area beyond 200 nm.Footnote ¹⁴⁸ As has been demonstrated, geology can play a role with regard to the determination of the seaward extent of the continental margin, but only in the context of the evidence to the contrary rule, ie as an exception to the general rule under Article 76(4)(b) of UNCLOS. By contrast, geology has a central role in the application of Articles 76(5)-(6) of the Convention, which obviously is also a nuance not reflected in the finding of ITLOS.

2. Developments by the CLCS

The CLCS has not been unaware of the need to clarify its understanding of the constitutive criteria for classifying a seafloor high as a submarine elevation that is a natural component of the continental margin. The Guidelines shed some light on the understanding of the CLCS in relation to key provisions in Article 76(6). The guiding criterion in the Guidelines is also geology, but in the context of whether the continental margin is activeFootnote ¹⁴⁹ or passive.Footnote ¹⁵⁰ The CLCS says that it is ‘relevant to consider the processes that form the continental margins and how continents grow’Footnote ¹⁵¹ in order to determine which seafloor highs are submarine elevations that are natural components of the continental margin. The CLCS notes for these purposes that the ‘growth of the present continents is and/or was primarily caused by geological processes along the continental margins’.Footnote ¹⁵² It is thus clear that the classification of a seafloor high as a submarine elevation that is a natural component of the continental margin according to the Guidelines is contingent upon the documentation of a geological continuity with the land mass from which such a seafloor high is the submerged prolongation.

The Guidelines are adopted by a treaty body and therefore not binding on States Parties to UNCLOS. It is nevertheless difficult to ignore that the above-mentioned references to geological factors are in a document seen as essential for determining, inter alia, which seafloor highs are submarine elevations that are natural components of the continental margin. It is noteworthy that provisional guidelines were submitted to States Parties and non-States Parties to UNCLOS for commentsFootnote ¹⁵³ prior to their adoption by the CLCS. While this exercise resulted in significant changes to various provisions, point 7.3.1 of the Guidelines, relating to constitutive criteria of submarine elevations that are natural components of the continental margin, is identical to the provision in its precursor. While the Guidelines cannot constitute a subsequent agreement within the meaning of Article 31(3)(a) of the Vienna ConventionFootnote ¹⁵⁴ it does not necessarily mean that they are deprived of normative characteristics. The fact that States were given the opportunity to comment on the Guidelines, provided that their comments to the CLCS were duly considered, could support the argument that the Guidelines should be considered to be a subsequent agreement for the purpose of treaty interpretation.Footnote ¹⁵⁵

In its Guidelines, the CLCS holds that it ‘designed these Guidelines with a view to ensuring a uniform and extended State practice during the preparation of scientific and technical evidence submitted by coastal States’.Footnote ¹⁵⁶ It could follow that there is a clear incentive for coastal States to interpret Article 76(6) in a manner which is meticulously consistent with the Guidelines. This is particularly so since opposability of outer limits of the continental shelf is made contingent upon these being established on the basis of the CLCS recommendations. Thus, States Parties tend to align their reasoning to that being expressed in the Guidelines. This could accordingly reflect a subsequent practice within the meaning of Article 31(3)(b) of the Vienna ConventionFootnote ¹⁵⁷ despite its being at the instigation of a treaty body. Such subsequent practice may, to use the expression of the arbitral tribunal in Interpretation of the air transport services agreement between the United States and France

Against this background, it is clear that the Guidelines must be considered relevant for determining which criteria are to be fulfilled in order for a seafloor high to constitute a submarine elevation that is a natural component of the continental margin. The practice of the CLCS indicates also that the criteria outlined in the Guidelines are applied in its assessments of whether the submitted data and documentation are sufficient to determine that a seafloor high is a submarine elevation that is a natural component of the continental margin. It should be noted that in its assessment of whether the ‘Ridge Part’ of the Izu-Ogaswara Arc could be considered a submarine elevation that is a natural component of the continental margin of Japan, the CLCS made explicit reference to point 7.3.1(a) of the Guidelines. Its reasoning underlying its decision not to consider the classification of the Ridge Part of this feature as a submarine elevation that is a natural component of the continental margin was based on the above-mentioned provision of the Guidelines, considering it to be ‘a submarine ridge in the sense of article 76, paragraph 6’.Footnote ¹⁵⁹ The same approach is also reflected in the recommendations to Australia. The CLCS did not accept that Joey Rise could be classified a submarine elevation that is a natural component of the continental margin: ‘Australia classifies the Joey Rise as a submarine elevation that is a natural component of the continental margin in the sense of article 76, paragraph 6 … The view of the Commission, however, is that the data presented on the origin of the Joey Rise is too sparse to be conclusive. Therefore the Commission does not consider it proven that the Joey Rise should be regarded as a submarine elevation that is a natural component of the continental margin in the sense of article 76, paragraph 6.’Footnote ¹⁶⁰

The practice demonstrates that CLCS considers geological continuity between the seafloor highs, on which the 2,500 m isobaths are located, and the relevant land mass of the submitting coastal State, a condition precedent for accepting proposed outer limits that are based on such seafloor highs. The CLCS has accordingly both dismissed and accepted the use of the depth constraint based on an assessment of whether or not the submitted data is considered to support an appropriate geological continuity from the seafloor high to the land mass from which it extends. Where a coastal State has failed to document geological continuity, the CLCS has refused to consider seafloor highs as submarine elevations that are natural components of the continental margin. Thus, a formal understanding of the CLCS appears to be established with regard to the processes for determining which seafloor highs are submarine elevations that are natural components of the continental margin and therefore eligible for use of the depth constraint in accordance with the second sentence of Article 76(6). This understanding is in line with the notions and developments that are outlined in the relevant provisions of the Guidelines. However, there remain several outstanding questions.

3. Required standard of proof

One difficulty is the standard of proof that is required to demonstrate geological continuity with the land mass. It is noteworthy that in its observations on whether Norway had demonstrated geological continuity between the Jan Mayen Micro Continent/Icelandic Plateau and the land mass of the Norwegian overseas island Jan Mayen, the CLCS approved Norway's documentation by applying an ‘on balance’ standard.Footnote ¹⁶¹ The same standard also appears in the CLCS recommendations to Australia. The CLCS held that ‘on the basis of the data and information presented the geological origin of the whole Wallaby Composite High still remains unresolved’.Footnote ¹⁶² Given the requirements under Article 76(6) of UNCLOS and the Guidelines, it might therefore have been expected that the CLCS would not accept the Wallaby Composite High as a submarine elevation that is a natural component of the continental margin of Australia. However, although the geological history remained unresolved, the CLCS held ‘[n]evertheless, on the balance of morphological and geological evidence presented, the [CLCS] agrees that the Wallaby Composite High is to be regarded as a submarine elevation that is a natural component of the continental margin in the sense of Article 76, paragraph 6’.Footnote ¹⁶³ This approach fails to offer meaningful or conclusive guidance about the extent to which geological data may be relevant, and thus is unhelpful to other States that will be seeking to classify seafloor highs as submarine elevations that are natural components of the continental margin.

More recently, a majority decision of the sub-commission established to consider the partial submission of Iceland dated 27 April 2009 appears to have agreed with Iceland's classification of Reykjanes Ridge as a submarine elevation that is a natural component of the continental margin of Iceland.Footnote ¹⁶⁴ Because of a disagreement on this issue, the CLCS was unable to take a positionFootnote ¹⁶⁵ on the recommendations of the sub-commission until its fortieth session.Footnote ¹⁶⁶ In its recent recommendations to Iceland, the CLCS held ‘that the data and information contained in the Submission were inconclusive to support the western and southern parts of the Reykjanes Ridge as a natural component of the continental margin of Iceland’.Footnote ¹⁶⁷ It remains unclear in what sense, or according to which criteria, this data was considered inconclusive. It is also difficult to confirm whether there is a substantive difference between a finding that the geological history of a feature is ‘unresolved’Footnote ¹⁶⁸ and a finding, for example, that the data and information submitted are ‘inconclusive’.Footnote ¹⁶⁹ Moreover, the CLCS has not explained why the data relating to the classification of the Wallaby Composite High was apparently deemed conclusive notwithstanding the geological origin of the seafloor high being ‘unresolved’Footnote ¹⁷⁰ while the data relating to the Reykjanes Ridge apparently is unresolved but inconclusive for the purpose of the second sentence of paragraph 6 of Article 76. Further, it appears that the CLCS is not in agreement regarding which data is conclusive for the purpose of such classifications. This becomes clear as ‘some members of the Commission accepted the consideration of the Reykjanes Ridge as a submarine elevation based on the data and information included in the Submission’.Footnote ¹⁷¹

It is difficult to draw conclusions from this. Consensus on the CLCS recommendations to Iceland was only reached ‘[f]ollowing extensive deliberations by the Commission [during which] the Chair of the Commission presented a proposal which became a basis for a consensual outcome of those deliberations’.Footnote ¹⁷² Thus, it would be wise not to draw firm conclusions from these summaries of recommendations. It should nevertheless not be excluded that, whilst framed otherwise, the disagreement relates to morphology rather than geology,Footnote ¹⁷³ assuming that morphology should also be a factor in classifying a seafloor high to be a submarine elevation that is a natural component of the continental margin. Whether morphology should have a say in this might have a determinative role for establishing the permissible seaward extent of entitlements to the outer continental shelf in the Central Arctic Ocean.

1. Classification of the Lomonosov Ridge

It was argued in an article from 1980 that ‘[b]y no stretch of imagination can oceanic ridges such as the Mid-Atlantic Ridge properly be regarded as falling within this definition of the continental margin, nor can the sides of these great mountain chains be regarded as the foot of the continental slope for purposes of applying the Irish formula’.Footnote ¹⁷⁶ The facts, as they present themselves today, suggest the contrary.Footnote ¹⁷⁷ This appears unambiguously in the recommendations of the CLCS to the United Kingdom regarding Ascension Island. The CLCS only refused to accept the proposed outer limits of the United Kingdom because the base of slope, and associated foot of slope points, was located at a distance that does not permit the establishment of an outer edge of the continental margin that extends beyond the 200 nm distance line.Footnote ¹⁷⁸ Thus, the refusal to accept the proposed outer limits of the United Kingdom did not relate to the geology of the seafloor high on which the United Kingdom sought to establish outer limits. The disagreement related only to the identification of the base of slope under Article 76(4)(b). This recommendation of the CLCS is relevant for the Central Arctic Ocean. A fortiori, if mid-Atlantic ridges can form part of the continental margin, nothing should prevent similar morphological seafloor highs forming part of coastal States’ continental margins in the Central Arctic Ocean. Rather, the question is whether narrow and elongated seafloor highs can constitute submarine elevations that are natural components of the continental margin.

There appears to be some evidence of practice by the CLCS indicating that it does not make morphological criteria a condition precedent for classifying a seafloor high as a submarine elevation that is a natural component of the continental margin. Thus, whether a seafloor high has a morphological shape of a ridge or plateau is irrelevant for the purposes of Article 76(6) of UNCLOS. This is true in so far as the seafloor high is geologically continuous with the land mass. It has been observed that ‘[t]he view that the inclusion of paragraph 6 in article 76 was intended to limit the continental shelf to 350 [nm] on submarine ridges of an oceanic origin is confirmed by a number of commentaries on the negotiations’.Footnote ¹⁷⁹ A fortiori, where the ridge-like feature is continental, and shares such characteristics with the land mass, it should not fall within the first sentence of Article 76(6). The Guidelines are instructive in this regard. The provisions in point 7.3.1 elaborate in some detail the ‘geological processes’Footnote ¹⁸⁰ that indicate constitutive criteria of submarine elevations that are natural components of the continental margins. These provisions do not include considerations relating to morphology. Thus, it must be assumed that the CLCS should not consider the morphological shaping of a seafloor high to be relevant for the purposes of classifying them as submarine elevations that are natural components of the continental margin.Footnote ¹⁸¹ This logic appears to be reflected in the CLCS recommendations to New Zealand in which various elongated ridge-like features were considered submarine elevations that are natural components of the continental margin and therefore subject to the more favourable constraint under Articles 76(5)-(6).Footnote ¹⁸² These CLCS recommendations could to some extent be considered relevant to the question of whether the Lomonosov Ridge can constitute a submarine elevation that is a natural component of the continental margin. This could not only be relevant for Russia but for other coastal States abutting the Central Arctic Ocean as well, including Denmark/Greenland.Footnote ¹⁸³

It appears in the recommendations to Russia from 2002 that the CLCS did not dismiss the idea that the Lomonosov Ridge is a submarine elevation that is a natural component of the continental margin of Russia. Russia states, in its revised partial submission relating to the Arctic, that the CLCS held with regard to its initial submission ‘that taking into account the information provided in the Submission, the Lomonosov Ridge cannot be considered as a submarine elevation under the Convention’.Footnote ¹⁸⁴ Rather, it would appear that the information provided in the submission of Russia was insufficient to draw this conclusion. This seems to stand in contrast to the views expressed by the United States that the Lomonosov Ridge ‘is a freestanding feature in the deep, oceanic part of the Arctic Ocean Basin, and not a natural component of the continental margins of either Russia or any other State’.Footnote ¹⁸⁵ Leaving aside the question whether the morphological setting enclosing the Lomonosov Ridge fits the characteristics of a ridge-like feature,Footnote ¹⁸⁶ the above comment of the United StatesFootnote ¹⁸⁷ appears to support the view that geometry is a constitutive criterion for the purpose of classifying a seafloor high a submarine elevation that is a natural component of the continental margin.

It should be noted that whilst several elongated ridge-like features were accepted as individual submarine elevations that are natural components of the continental margin of New Zealand, it would appear that the CLCS attached some importance to the particular morphological interrelations of these ridge-like seafloor highs. The CLCS did not consider the seafloor highs in question as freestanding features but part of a more complex system. The CLCS stressed that ‘[t]he Kermadec and Colville Ridges form a set of coalesced ridges with the Kermadec Ridge facing the Pacific Ocean to the east and the Colville Ridge facing the South Fiji Basin to the west’.Footnote ¹⁸⁸ Whether this helps the coastal States in the Central Arctic Ocean is unclear. Firstly, it is not clear whether they consider the Lomonosov Ridge to be part of a geological complex system within which the Alpha-Mendeleev Ridge System is an integral part or whether they consider them separate seafloor highs. Secondly, it is difficult to determine the meaning and scope of the notion of coalesced ridges and its possible implication for classifying the Lomonosov Ridge within either of the typologies of seafloor highs under Article 76(6) of UNCLOS. However, the CLCS is aware that submitting coastal States examine its summary of recommendations meticulously in order to see what support they can offer for their own claims.Footnote ¹⁸⁹

Against this background, it can be concluded that the classification of the Lomonosov Ridge as a submarine elevation that is a natural component of the continental margin is contingent upon the demonstration of morphological and geological continuity with the relevant land mass. While neither UNCLOS nor the Guidelines appear to attach any role to geometry for the purposes of classifying the seafloor highs as submarine elevations that are natural components of the continental margin, the practice of the CLCS does not appear to conclusively rule this out. Yet, as the recommendations to Iceland illustrate there appear to be opposite views on this very question within the CLCS.

2. Classification of the Alpha-Mendeleev Ridge System

According to established practice, the test of appurtenance with regard to the Alpha-Mendeleev Ridge can be conducted exclusively in accordance with Article 76(4) in which, when reliance is not made on the evidence to the contrary rule, geology does not have a constitutive role for determining the permissible outer edge of the continental margin. Assuming that the outcome of such an analysis identifies a common envelope of the continental slope, which provides for the establishment of an outer edge that extends beyond the 200 nm distance line, the question becomes one of whether this seafloor high is a submarine elevation that is a natural component of the continental margin.

The Executive Summary to the partial revised submission of Russia from August 2015 says that in its 2002 recommendations to Russia, the CLCS refused to classify the Alpha-Mendeleev Ridge System as a submarine elevation that is a natural component of the continental margin. In doing so, the CLCS referred to the ‘current state of scientific knowledge’Footnote ¹⁹⁰ relating to the geological history of this seafloor high. This stands in marked difference from the arguments given for refusing to recognize the putative classification of the Lomonosov Ridge as a submarine elevation that is a natural component of the continental margin of Russia. In relation to the Lomonosov Ridge the CLCS referred to the inadequacy of the documentation presented to the CLCS. By contrast, in dismissing the putative classification of the Alpha-Mendeleev Ridge as a submarine elevation that is a natural component of the continental margin, as presented in the submission of Russia in 2001, the CLCS refers to the very basis for understanding the geological setting in the region surrounding the Alpha-Mendeleev Ridge System. While the revised partial submission of Russia appears again to rely on the Alpha-Mendeleev Ridge System as being a submarine elevation that is a natural component of the continental margin, it appears that Denmark/Greenland have refrained from classifying it as such. The Executive Summary of the partial submission of Denmark/Greenland states that the ‘submitted data and other material in this Partial Submission do not provide for [the] classification [of the Alpha-Mendeleev Ridge System] as submarine elevations that are natural components of the Northern Continental Margin of Greenland’.Footnote ¹⁹¹ This suggests that it is not necessarily the extent of scientific knowledge about this seafloor high that points to the conclusion that the Alpha-Mendeleev Ridge System should not be classified a submarine elevation that is a natural component of the continental margin. Rather that there is a lack of sufficient data to support such a claim.

The outstanding question appears to be, what is the level of documentation required for large oceanic igneous provinces such as the Alpha-Mendeleev Ridge System, superposed with volcanic lava, to be considered as submarine elevations that are natural components of the continental margin of land masses with continental crust? To phrase this differently, what is the required level of geological affinity with the land mass necessary for such a large igneous province to constitute a submarine elevation that is a natural component of the continental margin? The CLCS recommendations to Australia could be instrumental in this regard, at least as concerns its appreciation of evidence provided by the submitting coastal State with regard to the geological history of the Wallaby Composite High. In its recommendations to Australia the CLCS recognized that ‘the geological origin of the whole Wallaby Composite High still remains unresolved’.Footnote ¹⁹² Given that the notions ‘submarine ridges’ and ‘submarine elevations’ are two ‘distinct legal categories’Footnote ¹⁹³ and that the geological setting around the seafloor high in question is unresolved, it would appear fair to assume that the Wallaby Composite High could not be considered a submarine elevation. However, the CLCS decided otherwise. Upon establishing that the geological history is unresolved, it found that ‘[n]evertheless, on the balance of morphological and geological evidence presented, the [CLCS] agrees that the Wallaby Composite High is to be regarded as a submarine elevation that is a natural component of the continental margin in the sense of Article 76, paragraph 6’.Footnote ¹⁹⁴ It would follow that merely because the supposed continental affinity of the Alpha-Mendeleev Ridge System with the coastal States abutting the Central Arctic Ocean is ‘unresolved’—to use the language of the CLCS— this does not necessarily preclude the recognition of this seafloor high as being a submarine elevation that is a natural component of the respective continental margins. Yet, the CLCS appears to have reached opposite conclusions in its recommendations to France regarding New Caledonia. France argued that the whole seafloor structure between the South Fiji basin in the east and the Tasman Sea in the west formed part of the submerged prolongation from New Caledonia. The CLCS was not able to accept this view ‘on the basis of uncertain nature of the crust beneath the New Caledonian Basin separating the Lord How Rise (with its northern extension into Fairway Ridge and Bellona and Chesterfield islands) and the Norfolk Ridge … Therefore the Subcommission recommended to France that the Lord Howe Rise should be viewed as one entity not connected to the ridges further east.’Footnote ¹⁹⁵ Thus, while the CLCS in some cases, despite having insufficient data to allow it to make a conclusive determination, has not refrained from endorsing coastal States classifications of seafloor highs as submarine elevations that are natural components of the continental margin, there are also precedents in which the apparent insufficiency of the data has caused such classifications to be rejected.

There are also situations in which there is no material reasoning in support of the CLCS's conclusion. This is a matter of concern, in particular in light of the fact that such recommendations a priori deprive the relevant coastal State of insight into how to seek to revise the submission with a view to overcoming the problems posed by inadequate documentation. It is difficult to draw firm conclusions from the CLCS recommendation summaries. This is mainly due to apparent contradictions regarding the required standard of proof to determine that there is sufficient and conclusive evidence to demonstrate that the relevant seafloor highs, which are sought to be classified as submarine elevations that are natural components of the continental margin, share geological characteristics with the land mass of the submitting coastal State. Yet, the excerpts above shed some light on the documentation required to evidence that large igneous provinces, such as the Alpha-Mendeleev Ridge System, are submarine elevations that are natural components of the continental margin. Whether the scientific understanding relating to the geological history of the Alpha-Mendeleev Ridge System has changed since the CLCS adopted its recommendations to Russia in 2002 is a matter for scientists to determine.Footnote ¹⁹⁶ This does not alter the firm understanding that the classification of such seafloor highs must be determined according to legal hermeneutics, to the extent that it relates to matters regarding the interpretation of Article 76(6) of UNCLOS. Yet, to a large extent, the application of that provision involves demonstrating whether there is a geological affinity connecting the Alpha-Mendeleev Ridge system with the land mass of the relevant States. Russia notes that the CLCS agreed to its position that ‘the Mendeleev-Alpha Rise [was] formed as a large volcanic oceanic plateau built on the oceanic crust of the Canada Basin after its opening as a result of passage of the magmatic “hot spot”’.Footnote ¹⁹⁷ However, the CLCS did not accept the Russian position concerning the ‘continental origin’Footnote ¹⁹⁸ of the Alpha-Mendeleev Ridge System.

Russia does not conceal its strong reservations about some of the conclusions of the CLCS. One such reservation relates to the fact that ‘[b]asalt samples, on the basis of which far reaching conclusions about the origin of the Mendeleev-Alpha Rise were made in 2002, were taken only in one place. Contradictory information was given about the composition of these volcanic rocks.’Footnote ¹⁹⁹ Russia takes the position that, while the documentation included in the initial submission was sparse, the revised submission is based on a developed pool of dataFootnote ²⁰⁰ and, it must be assumed, provides a more solid basis for accepting that the Alpha-Mendeleev Ridge System is a submarine elevation that is a natural component of the continental margin of Russia. It appears that Denmark/Greenland are less sure about the continental origin of the Alpha-Mendeleev Ridge System. It is stated in the publicly available data that whether the latter seafloor high ‘was emplaced on oceanic crust or continental crust is debated’.Footnote ²⁰¹ A recently published article by Russian scientists states that a bottom rock material study, the processing and analysis of which was used in the preparation of the updated Russian submission relating to the Arctic, has proved the existence of continental type of basement crust at deep water rises in the Central Arctic Ocean.Footnote ²⁰² However, reservations have been expressed concerning the interpretation of the Russian scientists.Footnote ²⁰³ These controversies clearly show that the key issue relating to the classification of the Alpha-Mendeleev Ridge Complex relates to the level of geological affinity with the land mass in order to classify this seafloor high a submarine elevation that is a natural component of the continental margin. This arises as this determination determines whether the seafloor high in question is subject to either of the constraints in Article 76(5), as it falls within the material ambit of the second sentence of paragraph 6 or whether it is subject to the more strict 350 nm distance constraint.

It is reasonable to assert that, failing the demonstration of geological affinity, the Alpha-Mendeleev Ridge System, or parts thereof, will be considered submarine ridges on which the outer limits cannot exceed 350 nm from the baselines. It can thus be concluded that the claims of the Arctic States to outer continental shelf entitlements will depend on complex geological considerations. This is true with regard to both the classification of the Lomonosov Ridge and the Alpha-Mendeleev Ridge System. Thus, while ITLOS has made it clear that a significant geological discontinuity does not prevent an entitlement extending beyond 200 nm,Footnote ²⁰⁴ this does not mean that geology is irrelevant for determining the seaward extent of entitlement to the outer limits of the continental shelf. Quite the contrary. Geology is given a pivotal role for determining whether entitlement extends beyond the 350 nm distance constraint line. Thus, the entitlements to large areas of the Central Arctic Ocean are contingent upon their fulfilling geological criteria, since large areas of claimed entitlements depend on seafloor highs being classified as submarine elevations that are natural components of the coastal States respective continental margins.