98 THE OCEAN FLOOR 



that found in the "Albatross" cores might have become 

 distributed over the adjacent sea bottom. However, 

 apart from the general improbability of this explana- 

 tion, the prevailing surface currents at present run from 

 southeast to northwest, that is, in a direction opposite 

 that in which the transportation of sand, foram shells, 

 and vegetable remains might have been supposed to 

 occur. In this dilemma both Locher and Phleger have 

 accepted the explanation of transportation by turbidity 

 currents. This would mean that some very considerable 

 submarine landslides occurring on the shelf off or near 

 the Amazon Estuary produced a sediment-laden bot- 

 tom current of great intensity, extending far enough to 

 transport coarse and unsorted material over a distance 

 of several hundred miles along a slope which cannot 

 on an average have been greater than 1:200, an ex- 

 planation which is difficult to accept. 



The mystery of the deep-sea sand in this part of the 

 equatorial Atlantic Ocean cannot be considered solved. 

 We may only hope that future expeditions to this region, 

 taking long cores and multiple echogram lines between 

 the locality indicated and the Amazon Estuary, will 

 throw light on this fascinating problem. 



A most interesting mineralogical study was made by 

 O. Mellis of Stockholm on stones found in a core taken 

 at lat. 29° 21' N., long. 58° 59' W., southeast of Ber- 

 muda in a depth of 5,450 meters.^ The weathering 

 crust on these stones proved beyond doubt that a trans- 



