72 ' ' MARION ' ' EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



in less than 150 meters of water have medians of T and 2.3 microns, 

 respectiveh^ but sample 22 on a fairly steep slope in 1,650 meters 

 has a median of 73 microns. Samples 23, 24, and 25 lying in about 

 200 meters of water in a region of uneven sea floor have medians 

 of 44 to 162 microns. 



The phenomena mentioned above demonstrate that the texture of 

 the sediments is strongly influenced by the submarine topography. 

 However, in reality it is the motion of the sea water above the de- 

 posits that governs the size of the particles that accumulate in the 

 sediments. The movement of the deep water is deflected and ob- 

 structed by submarine slopes and ridges. In this manner relatively 

 strong currents are produced over many exposed slopes and ridges.^ 

 In fact, the relative coarseness of the deposits is a measure of the 

 intensity of the movement of the low^er part of the sea water, 



Gun^ents. — Smith and Mosby's ^ detailed investigation of the cir- 

 culation of the water in Davis Strait, shows that a strong w^esterly 

 current swings around Cape Farewell and up the west coast of 

 Greenland. At various intervals as far north as latitude 75°, parts 

 of it bend w^estward and slowly cross Davis Strait, where they join 

 a strong southerly current, coming from Lancaster Sound. This 

 southerly current continues down the east coast of Baffin Land across 

 Hudson Strait and southward along the coast of Labrador. The 

 dynamic topographic map of this region sliows that in general the 

 movement of water is parallel to the trend of the submarine slopes 

 and scarps and that it is relatively rapid over steep slopes. The 

 greatest intensity of circulation is in the upper layers of the water ; 

 but the coincidence of the relatively rapid movement of the upper 

 part of the sea water with the coarseness of the deposits ofi^ Cape 

 Farewell, ofi^ Cumberland Peninsula, and on the continental slope 

 off Resolution Island and northern Labrador, demonstrates that in 

 these regions the lower part of the sea water, especially that bathing 

 the sea bottom, move with significant velocit5^ However, the 

 movement of the deep w^ater may be due to tides and not gradient 

 currents. 



The extremely fine sediments in the relatively shallow water off 

 Aulalsivik lie in regions in which the dynamic gradient of the sea 

 water is slight. This indicates that the circulation of the surface 

 water is slow\ The deposition of sediments having medians of 

 7 and 2.3 microns, in water less than 150 meters deep, demonstrates 

 that the lower part of the water also is quiescent. The low gravel 

 content likewise argues against strong current action. A similar 

 explanation accounts for the large quantit}^ of fine particles in 

 sample 8, about 100 miles northeast of Cape Murchison. 



The coarseness of the sediments of Hudson Strait indicates that 

 they are washed by strong currents. Even though they lie in 575 

 meters of water they are very well sorted and have a median of 208 

 microns, which indicates that they are a medium to fine grained 

 sand. Smith and Mosby's dynamic topographic map indicates only 

 a slight circulation of water in this region, but it refers to move- 



^ See P. D. Trask, Op. cit., pp. 28-33. 



8 Edward II. Smith and Olav Mosby, The Physical Oceanography of Davis Strait, 

 pt. 2 of Bulletin 3 9. 



