THE INTERIOR OF THE EARTH. 227 



tions imply should have made themseh^es felt proportionately on 

 any great mass of liquid in the interior, if it were in existence, 

 and extrusions proportionate to the greatness of the deformations 

 should have accompanied such diastrophism. But, while liquid ex- 

 trusions took place somewhat freely at the times of great dias- 

 trophism, it was not, at least in my judgment, at all commensurate 

 with the deformative stresses implied by the diastrophic results 

 shown in the solid material. 



Nor was the topographical concentration of the extrusions indica- 

 tive of their origin from a molten interior or from really great 

 residual reservoirs of liquid rock. If such ample sources of liquid had 

 existed, they might naturally have been expected to have given forth, 

 under the great stresses then seeldng easement, correspondingly great 

 floods of lava which would have gone far to fill the great basins into 

 which they must chiefly have flowed. Yet no single lava flood seems 

 to have attained more than an extremely small fraction of the mass of 

 the earth, or even of the known solid matter of the immediate region 

 of the outflow. Even when the sum total of the most massive series 

 of successive floods in a given region are taken together — though the 

 successive issues stretched over a considerable period — they rarely 

 rise above a most insignificant fraction of earth mass, or even of the 

 regional segment of it with which they are associated. Instead of 

 really massive flows, implying ample sources of supply and great 

 forces of extrusion, the record shows rather a multitude of little 

 ejections or injections of more or less sporadic distribution. The 

 logical implication of these is the preexistence of a multitude of 

 small liquid spots, or liquifiable spots, scattered widely through the 

 stressed earth masses and yielding to stress as local conditions re- 

 quired and where local conditions required. 



This inference is pointedly supported by the great variations in 

 altitude at which lavas are now given forth and seem to have always 

 been given forth so far as the record goes. The most impressive 

 illustrations of this are found in current volcanic action where the 

 relations in altitude are precisely loiown. So far as ancient condi- 

 tions can be restored, they appear to fall into the same general class 

 as existing conditions. Current outpourings of lava range from the 

 sea bottom to altitudes of many thousands of feet above sea level, a 

 vertical range of several miles. Extrusions occur at these signifi- 

 cantly diverse altitudes simultaneously or alternately or in almost 

 any time relations, and sometimes in the most marked independence 

 of one another, in spite of the natural sympathy which such events 

 might naturally manifest in a common stressed body. A multitude 

 of facts of detail, some of which are singularly cogent, imply that 

 the lava sources of present volcanoes are disconnected from one an- 

 other in the interior, and are hence independent in action, as a rule, 



