I48 THE FLOOR OF THE OCEAN 



laboratory. Knowing that experiment is the principal tool of 

 science, Dr. P. H. Kuenen of Holland has called on the re- 

 sources of the laboratory. He had three objectives: to devise a 

 visual test of the possibility that silty currents can long preserve 

 their individuality even though the motivating silt tends to 

 settle out; second, to measure the velocities under controlled 

 conditions regarding current density and slope of channel; 

 and, third, to determine whether a current, flowing fast, will 

 add to the suspended load and therefore run still faster. 

 Kuenen succeeded with all three problems, and not the least 

 significant of his conclusions is that a strong bottom current 

 running down a continental slope may readily become self- 

 accelerating and thus endowed with new, self-generated power 

 to erode. Some of his experiments will be briefly described. 18 



In a glass-walled tank, 15 feet long and 2 feet deep, a model 

 of a "continental terrace" was built of sand surfaced with hard 

 gypsum. The "shelf" had a gentle slope as far as the fall-off to 

 the "continental slope," which had a gradient of about 1 in 10 

 or one typical of the upper part of the average continental slope 

 in Nature. Water was poured into the tank until it topped the 

 "shelf" by a few millimeters or centimeters. Just above the fall- 

 off a strip of wood with a rubber flange at the bottom was 

 placed all across the tank. Back of this bar, water with various 

 proportions of solid particles in suspension was gently poured 

 on the "shelf." The bar was then removed. The silty water at 

 once began to flow down the "continental slope" in the form 

 of a lively bottom current. These initial steps in experimenta- 

 tion are represented in the three cross-sections of Kuenen's 

 diagram, Figure 75. Figure 76 is a photograph of the tank, 

 whose scale can be gaged by the width of each pane of glass, 

 namely, about three feet; the terrace is shown in profile. 



It was found that any slight crease or depression directed 

 down the "continental slope" tended to draw the silty water 



