282 CHAMBERLIN— THE INTERIOR OF THE [April 24, 



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 required. 



This inference is supported by the great variations in altitude at 

 which lavas are given forth. The most impressive illustrations of 

 this are found in current volcanic action whose relations in altitude 

 are precisely known. So far as ancient conditions 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 significantly 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 of such events 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 another in the interior, and hence independent in action, as 

 a rule, though sometimes they show sympathy without showing 

 liquid connection. The sources of lava seem to be meager in gen- 

 eral, and the eruptive agencies seem to be controlled by narrowly 

 local conditions. There is an absence of evidence that the lavas in 

 the craters and necks of volcanoes are parts of great liquid masses 

 below, responsive to the common stresses of a large region. 



Thus geological evidence, when critically scrutinized, seems to be 

 distinctly adverse to the existence of even large reservoirs of molten 

 matter within the earth ; it points rather to the presence of scattered 

 spots, very small relatively, on the verge of liquefaction, which pass 

 by stages into the liquid form and are then forced out by the dif- 

 ferential stresses that abound in the earth body, each such local liqui- 

 fying center commonly giving forth driblets of lava and gas, at in- 

 tervals, none of which often rise to more than an extremely minute 

 fraction of the earth mass or even of the subterranean mass con- 

 tiguous to the volcano. 



