FOUNDATIONS OF THE GREAT DEEP 



41 



FIGURE 20. MAP SHOWING IN METERS THE AMOUNT OF UPWARP STILL 



NEEDED TO BRING THE EARTH'S CRUST OF THE FENNOSCANDIAN REGION 



INTO BALANCE WITH THE CRUST ELSEWHERE. AFTER E. NISKANEN. 



from the periphery of the glaciated tract. When the inflow is 

 completed, a vertical column of this material under the central 

 point of the glaciated land will have the same mass as that of 

 a column of granite a little over 700 feet in height. 



The other way of estimating the mass still to be thrust into 

 the central region and so bring the earth's crust into stable 

 balance, is based on measurements of gravity at many points in 



