30 THE FLOOR OF THE OCEAN 



computed the Bouguer anomalies. In both instances he found 

 these anomalies to be strongly positive. He used the ordinary 

 unit, the milligal, which is very close to being one millionth 

 of normal gravity. His values for the anomalies are given by 

 the underlined numbers in the top and bottom maps in Figure 

 14. The values are positive to such a degree that there cannot 



ATLANTIC 



OCEAN 



FIGURE 14. MAPS SHOWING BOUGUER AND ISOSTATIC ANOMALIES OF GRAVITY 

 ALONG TRAVERSES OF PACIFIC OCEAN, NORTH AMERICA, AND ATLANTIC 



OCEAN. 



be any deficiency of matter under the ocean. This means that 

 the density of the rock below the oceanic ooze is considerably 

 higher than the density of average continental rock. The con- 

 clusion is all the more certain in view of the fact that the 

 Bouguer anomalies on high ground of the United States are 

 strongly negative. To see this, note the underlined figures in 



