FOSSIL FORAMINIFERA FROM THE 



BURDWOOD BANK AND THEIR 



GEOLOGICAL SIGNIFICANCE 



By W. A. Macfadyen, M.C, M.A., Ph.D., f.g.S. 

 Sedgwick Museum, Cambridge 



(Text-figs. 1,2.) 



FOSSIL Foraminifera were recognized in bottom deposits from several stations of 

 the R.R.S. 'Discovery 11' and the R.R.S. ' WiUiam Scoresby'\ and in the present 

 investigation samples dredged from three stations on the northern part of the 

 Burdwood Bank were examined. 



DESCRIPTION OF SAMPLES 



I. A dredging at St. WS 87 in lat. 54° yi' S, long. 58° 16' W, dated 3. iv. 1927, 

 came from a depth of 96 m. It yielded a bottom sample comprising sand, with recent 

 shells and Foraminifera, etc., together with many fragments of shale, and loose fossil 

 Foraminifera. 



The shale all consisted of rounded pebbles, the largest of which measured 

 7x6x3 cm. The larger pebbles were partly stained by a brown surface coloration 

 and were pierced by borings, up to 6 mm. in diameter, of present-day marine organisms ; 

 several recent specimens of Polyzoa and Foraminifera were adherent to their surface. 

 The shale was of two kinds, both being rather hard, but showing no sign of crushing 

 or thermal metamorphism. Most was of a green-grey colour, highly glauconitic (best 

 seen at the eroded surface where the glauconite grains were left prominently exposed), 

 and very finely sandy. Traces of the original bedding were visible in some of the pebbles. 

 The less common type consisted of slightly sandy micaceous shale, light grey when 

 dried, and of exceedingly fine texture, without glauconite. There was a single pebble, 

 2-5 cm. long, of rather soft grey argillaceous limestone. 



The loose Foraminifera examined numbered about no and were in many cases 

 badly crushed and distorted, while some were preserved as calcite casts. Haplophrag- 

 tnoides subglobosiis and species of Cyclammina were the commonest forms. Mr Earland 

 found a number of the specimens specifically and some generically indeterminable, a 

 conclusion I fully share. Thirteen, all of arenaceous species, had traces of green finely 

 sandy shale adhering to them. 



The two kinds of shale were washed separately for Foraminifera. Nearly all of those 

 obtained came from the fine light grey shale, with Spiroplectammina spectabilis and 



1 See Heron-Allen, E., and Earland, A., 1932, Foraminifera. Part I, The Ice-free Area of the Falkland 

 Islands and Adjacent Seas, Discovery Reports, iv, pp. 297-8, Cambridge. 



