196 DISCOVERY REPORTS 



63 40' W, the other towards the outer part of the continental shelf in lat. 48 30' S, 

 long. 61 ° 50' W, both of type E3. 



GROUP F 



An extensive area of deposits of this group covers the deep-water region between the 

 Burdwood Bank and the Falkland Islands, and the Burdwood Bank and Tierra del 

 Fuego. It covers the floor of the bay of deep water stretching north between the Falk- 

 land Islands and South America, and becomes constricted to a narrow neck west of 

 the Jason Islands. To the north it opens out widely again and covers the continental 

 shelf north of the Falkland Islands east of long. 62 W as far north as lat. 48 20' S. 

 From this point the area stretches south to the north coast of West Falkland Island. 

 To the north-east deposits of group F cover the continental slope as far north as 

 lat. 47 S, where they again extend up on to the continental shelf as far west as long. 

 6i° 30' W. 



In the portion of the area north of the Falkland Islands, the eastern parts on the con- 

 tinental slope and on the continental shelf north of West Falkland Island are covered 

 by deposits of type Fi, except in lat. 47 40' S where a patch of type F3 lies on the 

 continental slope. The remainder of this area on the continental shelf is covered by 

 deposits of type F2, while a patch of type F4 occurs at its north-west corner in lat. 49 S. 



The narrow part of the group F area west of the Jason Islands consists of deposits of 

 type F2, as does the central and deeper part of the area between the Falkland Islands 

 and Tierra del Fuego. The northern part of the deep water bay and its eastern and 

 western slopes are covered by deposits of type F 1, while a patch of type F3 lies on the 

 western slope adjacent to the patch of type E3. 



A wedge-shaped area of deposits of group F lies in the middle of the continental shelf 

 between latitudes 44 and 47 S, the point of the wedge being directed southwards. The 

 deposits are of type F 1 except at the pointed southern end of the area where they are 

 of type F2. 



The third area covered by deposits of this group is a coastal belt running from Point 

 Deseado to Point Santa Cruz, consisting of type F2. 



DISTRIBUTION OF THE DEPOSITS BY THE TEXTURE 

 OF THE SAMPLES AS A WHOLE 



Having detailed the distribution of the various component textures and types of the 

 bottom deposits, the division of the region into grounds based on the texture of each 

 sample as a whole is now considered. The results are shown in Plate XIV. 



In order to arrive at a value for the texture of the deposits which may be plotted com- 

 paratively the following procedure is adopted. In each sample the percentage of each 

 grade of material is multiplied by the minimum diameter of the particles occurring in the 

 grade, with the exception of the silt grade. The silt grade is omitted as the minimum 

 diameter of the particles composing it is infinitely low. The figures for each grade thus 

 obtained are added together and divided by 100, the resulting index number being the 



