Shearing Resistance, s 
Normal Pressure, p 
Figure 29. Relation between normal pressure and shearing resistance. 
A comparison of the data obtained by the Naval Oceanographic 
Office (Keller, 1968), shows that sediments in the North Atlantic possess 
relatively higher shear strengths than do those of the North Pacific. Large 
areas in the northern portion of the North Pacific consist of sediments 
possessing shear strengths ranging from 0.25 to 0.5 psi for the upper few 
feet of sediment. In the lower latitudes of the North Pacific, values of 
1.0 to 1.5 psi predominate, and in a few small areas values range as high 
as 1.5 to 2.5 psi. In the North Atlantic, sediments with a shear strength of 
0.5 to 1.0 appear to predominate. The highest values observed in the North 
Atlantic are associated with calcareous deposits and vary from 1.0 to 1.5 
psi, but there is one rather large area of red clay east of Greenland which 
displays strengths of less than 0.5 psi. For comparative purposes, a piece 
of modeling clay into which a person can push his thumb easily has a shear 
strength of approximately 2 to 3 psi. 
As shear strength is easily measured, It is used as a means of 
classifying soils, but when a load such as a platform or a vehicle track is 
applied, the load-bearing capacity is a more useful index of the soil strength. 
Figure 30 illustrates the relationship between shear strength and ground load- 
bearing capacity. As the load sinks into the soil, it pushes a cone of soil ahead 
37 
