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MAEIOX ' ' EXPEDITION TO DAVIS STRAIT AXD BAFFIN BAY 67 



Furthermore, these three constants afford a mathematical basis for 

 comparin^r sediments with each other. They demonstrate clearly 

 differences in general texture. de<j:ree of sorting of entire sample, and 

 position of maxinuun sortin<r within the deposit. They, of course, 

 are not substitutes for a complete analysis, but they do give most of 

 the important features of the mechanical composition. 



DESCRIPTIOX OF SEDIMENTS 



Texture. — The sediments are characterized by the plentifulness of 

 rock fragments. Table 3. column 2, and Figure 49 show the distribu- 

 tion of gravel in Davis Strait. Sample 27, located more than 500 

 miles south of the other sediments, is the only deposit in Avhich no 

 rock fragments occur. The average gravel content of the sediments 

 is 14 per cent and the maximum is 29 per cent. The distribution of 

 rock fragments is random in nature, which indicates that gravel is 

 fairly uniformly scattered over the sea floor in this region. Samples 

 15 and 16, lying in deep water far from shore, contain only 4 per 

 cent gravel, but until this relatively low content is supported by addi- 

 tional evidence one hesitates to infer a decreased gravel content in 

 the central part of Davis Strait. 



The variation in texture of the sediments, as indicated by the 

 median diameter and coefficients of sorting and skewness, are shown 

 in Figures 47 and 48. The presence of large quantities of gravel in 

 some samples makes the coefficient of sorting large, and masks the 

 sorting of the sands. The longitudinal series of samples lying in 

 400 to 700 meters of water off Cumberland Peninsula, with the excep- 

 tion of sample 1, which lies in a deep depression, are well-sorted, fine- 

 grained sands, having median diameters ranging betAveen 135 and 

 260 microns. Similarly, sample 19 in 575 meters of water in the 

 middle of Hudson Strait and sample 26 in 462 meters off Cape Fare- 

 well, Greenland, are well-sorted, fine-grained sands. Likewise, the 

 deposits on the two sections eastward from Cape Murchison lying 

 in 200 to 250 meters of water are well-sorted fine-grained sands. 

 Sample 8, however, in 290 meters, although containing a fairly large 

 amount of very fine-grained sand (21 per cent) has 12 per cent of 

 clay and 22 per cent of colloid ; consequently it is an extremely poorly 

 sorted, fine-grained sand. 



Sample 15 in 1,500 meters of water, at the seaward end of the sec- 

 tion southeastward from Cape Murchison, is a somewhat poorly 

 sorted, medium-grained silt. Similarly, the three samples forming 

 the section eastward from Resolution Island, lying in water 700 to 

 2,300 meters deep, are silts. They contain 30* to 45 per cent clay 

 and colloid and are fairly poorly sorted. 



The texture of sediments eastward from Aulalsivik, at the north- 

 ern tip of Labrador, varies considerably. Sample 20 in 65 meters 

 of water relatively near shore is a fine-grained silt, having a median 

 of 7 microns; specimen 21 in water 152 meters deep, about 10 miles 

 seaward, is a medium-grained clay having a median of 2.3 microns; 

 and sample 22 in 1.650 meters of water, 125 miles farther off shore, 

 is a poorly sorted fine-grained sand having a median of 73 microns. 

 The maximum amount of sorting in the last sample is in the fine- 

 grained sand group. 



