Chapter III 

 THE SEDIMENTS 



Parker D. Trask 

 INTRODUCTION 



This paper ^ presents detailed mechanical analyses and brief petro- 

 logic descriptions of 27 deposits collected by the Marion expedition 

 to Davis Strait. The practicability of the fundamental constants of 

 the size distribution of sediments, namely, the median diameter, and 

 the coefficients of skewness and sorting is discussed. The deposits 

 contain much ice-borne detritus. Faceted, subroundecl pebbles are 

 fairly uniformly distributed in the sediments over the entire region. 

 They constitute 14 per cent of the deposits. Gneiss, quartzite, and 

 aphanitic limestone are the predominant rock types. The nearest 

 source of the limestone seems to be in northern Greenland or the 

 Arctic northwest 500 to 1,000 miles away, but the areal geology of 

 northern Baffin Land is imperfectly known, and the limestone may 

 come from nearer regions not yet explored. The texture of the 

 sediments varies with the configuration of the sea bottom and with 

 the surface currents and tides. The deposits are relatively coarse 

 on steep slopes and also in Hudson Strait, off Cumberland Bay, and 

 on the transverse ridge that separates Davis Strait from Baffin Bay. 

 The presence of 1 to 4 per cent of frosted, well-rounded sand grains 

 suggests an eolian origin for some of the constituents. The fine 

 sediments contain from 20 to 40 per cent calcium carbonate, which 

 is in a finely comminuted state. Its association with the limestone 

 rock fragments in the deposit suggests that it is derived from 

 detritus carried by ice. 



GENERAL REMARKS 



This paper does not purport to be a comprehensive study of the 

 sediments of Davis Strait. Its object is to present and interpret cer- 

 tain data that are available. The writer has been aided by Harald E. 

 Hammar and M. A. Clark in determining the organic and carbonate 

 content of the sediments and by John Lucke and F. B. Walcott in 

 making the mechanical analyses. The description of the mineral 

 and rock constituents of the sediments are based on hand-lens deter- 

 minations and, therefore, are not as satisfactory as if they were the 

 result of microscopical examination. 



1 This paper, written by Trask, represents results arising from an investigation on 

 " The Origin and Environment of Source Beds of Petroleum," listed as project 4 of the 

 American Petroleum Institute Research program. Financial assistance in this work has 

 been received from a research fund of the American Petroleum Institute donated by 

 Mr. John D. Rockefeller. This fund is being administered by the institute with the 

 cooperation of the National Research Council. 



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