special mechanism was delineated during the CNUDM III to validate the legitimacy
of such limits and set them to be final and binding.
3 Article 76 and the Outer Edge of the Continental Margin
There were several factors that contributed most to the final provisions of Article
76, prescribed as the combinations of all related formulas. Among these the most
important were the access to existing mineral resources and its impact at socioeconomic level, and also the fact that the outer boundary of the Continental Shelf
would also be the boundary of the International Seabed Area.
12 Nonetheless, to set
an acceptable bordering limit, the legal framers needed to model the related universe
of discourse.
The primary model provided was a theoretical one representing the classical
physiographic continental margin. The conditions portrayed by this model occur in
some areas (Passive margins—Atlantic like margins) but are not universally
accepted as a whole.
13 Therefore, a second model was considered to analyse
where the type of continental margin does not contain a simple pattern as the
previous one. In this second type, seismic activity and block fragmentation on the
continental crust was commonly represented (Active margins—Pacific like margins). From the analysis of these models, several limits for the legal continental shelf
were suggested. Those were based on water depth, natural boundaries and crustal
boundaries. However, no agreement could be reached based on these parameters.
Two major contributions for the final agreement were given by Hedberg (1979)
and Gardiner (1978). Their knowledge over the complexity of the continental
margins allowed two different approaches for setting the outer limits. Hedberg
proposed that the national-international boundary for mineral resources of the oceans
should lie just oceanward of the continental slope, within a zone of an internationally
agreed width. Within that zone, each coastal State should draw its own precise
boundary by means of straight lines connecting geographic points. The initial width
for boundary zone proposed by Hedberg was 100 km, where the boundary between
oceanic and continental crust was expected to lie. This proposal evolved to what is
known as the Hedberg line.
Gardiner found the latter proposition inconsistent with the known scientific
definition of the natural prolongation of the landmass. He suggested that, if based
on true geological sense, the natural boundary of the continental margin would be the
outer limit of the continental rise, therefore, the sediment thickness boundary. The
“sediment thickness” formula
14 shapes the cut-off line in direct proportion to the
12 This was actually the need for a satisfactory basis for drawing the line between national and
international jurisdictional domain for mineral resources.
13 Monahan and Macnab (1994), p. 89.
14 Usually referred as the Gardiner Line.
11 The Challenges of the Commission on the Limits of the Continental Shelf
195
of such limits and set them to be final and binding.
3 Article 76 and the Outer Edge of the Continental Margin
There were several factors that contributed most to the final provisions of Article
76, prescribed as the combinations of all related formulas. Among these the most
important were the access to existing mineral resources and its impact at socioeconomic level, and also the fact that the outer boundary of the Continental Shelf
would also be the boundary of the International Seabed Area.
12 Nonetheless, to set
an acceptable bordering limit, the legal framers needed to model the related universe
of discourse.
The primary model provided was a theoretical one representing the classical
physiographic continental margin. The conditions portrayed by this model occur in
some areas (Passive margins—Atlantic like margins) but are not universally
accepted as a whole.
13 Therefore, a second model was considered to analyse
where the type of continental margin does not contain a simple pattern as the
previous one. In this second type, seismic activity and block fragmentation on the
continental crust was commonly represented (Active margins—Pacific like margins). From the analysis of these models, several limits for the legal continental shelf
were suggested. Those were based on water depth, natural boundaries and crustal
boundaries. However, no agreement could be reached based on these parameters.
Two major contributions for the final agreement were given by Hedberg (1979)
and Gardiner (1978). Their knowledge over the complexity of the continental
margins allowed two different approaches for setting the outer limits. Hedberg
proposed that the national-international boundary for mineral resources of the oceans
should lie just oceanward of the continental slope, within a zone of an internationally
agreed width. Within that zone, each coastal State should draw its own precise
boundary by means of straight lines connecting geographic points. The initial width
for boundary zone proposed by Hedberg was 100 km, where the boundary between
oceanic and continental crust was expected to lie. This proposal evolved to what is
known as the Hedberg line.
Gardiner found the latter proposition inconsistent with the known scientific
definition of the natural prolongation of the landmass. He suggested that, if based
on true geological sense, the natural boundary of the continental margin would be the
outer limit of the continental rise, therefore, the sediment thickness boundary. The
“sediment thickness” formula
14 shapes the cut-off line in direct proportion to the
12 This was actually the need for a satisfactory basis for drawing the line between national and
international jurisdictional domain for mineral resources.
13 Monahan and Macnab (1994), p. 89.
14 Usually referred as the Gardiner Line.
11 The Challenges of the Commission on the Limits of the Continental Shelf
195