MARINE DEPOSITS OF PATAGONIA 193 



grades consist of dark and light grey grains with some brown, yellow, or white grains. Foraminifera 

 are present in some numbers in WS 833, while fine fragments of coral form a conspicuous part of 

 the finest grades of WS 766. Silt grey to greyish green. Eight samples, WS 89, WS 238, WS 245, 

 WS 762, WS 766, WS 788, WS 833, WS 834. 



Type E4. Light grey gravel composed of irregular but slightly rounded fragments of soft grey 

 stone or very hard grey clay, with some greyish-brown pebbles and gravel in the coarsest grades. 

 Bivalve, gastropod, and brachiopod shells and fragments are numerous in the medium grades. Silt 

 yellowish brown. This type is quite distinct from all the other types of group E. One sample, WS 841. 



GROUP F. GREYISH-GREEN SAND AND SILT 



Type F i . Medium to dark coloured greyish-green muddy sands of fine texture, consisting almost 

 entirely of grades fine sand and silt. A few samples have small shell fragments and grey or brown 

 gravel in small proportions in the coarser grades. The finer grades are grey to greyish green, with 

 some admixture of white grains in some cases. Silt greyish green through green to light yellowish 

 green. Thirteen samples, WS 99, WS 211, WS 212, WS 214, WS 232, WS 236, WS 244, WS 756, 

 WS 773, WS 790, WS 791, WS 821, WS 839. 



Type F2. Greyish-green muddy sands lighter than those of type Fi by reason of the larger ad- 

 mixture of yellow and white grains, as well as lighter grey and greyish-green grains. Fine in texture, 

 with a small proportion of shell and coral fragments, dark and light grey, white, and yellow gravel 

 in the coarser grades of some samples. Foraminifera occur in small numbers in some samples. Silt 

 dark greyish green through green to yellowish green. Nine samples, WS 76, WS 210, WS 239, 

 WS 775, WS 783, WS 784, WS 810, WS 819, WS 820. 



Type F3. Darker greyish-green sands of coarser texture than type F2 with coral (Turbinolid) 

 forming a large proportion of the coarser grades in which there are also some grey pebbles. The finer 

 grades are mixed with coral detritus. Silt dark greyish green. Two samples, WS 215, WS 818. 



Type F4. A light greyish-green type of coarse texture with some grey and brown stones and a 

 high proportion of gravels composed of grey, greyish-green, brown, and yellow pebbles. Small 

 fragments of shell and echinoderm spines occur, while Foraminifera are conspicuous in the finer 

 grades. Silt green. One sample, WS 97. 



DISTRIBUTION OF THE TYPES 



The types described above are distributed in well-defined areas mostly covering wide 

 expanses of the sea-bottom. Plate XIII shows the distribution of the types by group, 

 and the occurrence of the various types within the groups is described below. 



GROUP A 



The distribution of the types assigned to group A is confined to the southern part 

 of the region examined. They occur as a coastal belt off the west and south shores of 

 the Falkland Islands from a little north of the Jason Islands to long. 58 30' S on 

 the south coast, but not in Falkland Sound. A patch extends in a north-easterly 

 direction from the north coast of East Falkland Island to the edge of the continental 

 slope. In the northern part of the coastal belt the types are A 1, passing through A3 off 

 the south coast of West Falkland Island and Falkland Sound to A4 off the south coast 

 of East Falkland Island. The patch to the north-east of the islands is entirely A 4. 



On the Burdwood Bank there is a patch on the northern slope consisting of type A 2. 

 Farther to the west, north of the western extremity of Tierra del Fuego, lies another 

 patch of deposits assigned to this group and consisting of type A 5. 



3-2 



