THE APPEARANCE OF LIFE ON THE GLOBE 333 



the designation of Crystallophyllian soil, which is 

 very apt, and has been favourably received by the 

 learned world. The term Archean soil is also very 

 frequently used. 



Very few geologists at the present day refuse 

 to admit that these schistous and crystalline 

 strata with surfaces sparkling with spangles of 

 mica and sericite, must have been originally true 

 amorphous sediments deposited in the state of 

 slime, sand, and limestone at the bottom of the 

 primitive oceans. The presence of perfectly pre- 

 served calcareous bands, of beds of sandstones, and 

 of conglomerates recalling to mind the early sand and 

 pebbles of the seashore, and the frequent parallelism 

 of these strata with that of the pre-Cambrian and 

 Cambrian soil which covers them, are strenuous 

 arguments in favour of this point of view, which 

 has been championed in France by Michel Levy. 

 What kind of mechanism is it that has produced 

 this profound metamorphic modification of ancient 

 sediments thus changed into the state of crystalline 

 rocks almost similar to eruptive rocks ? It is 

 necessary, in order to arrive at anything like a clear 

 idea of this, to cast a glance on the series of phe- 

 nomena which have accompanied the deposit of 

 marine sediments during the long series of geological 

 ages. These sediments, of almost wholly conti- 

 nental origin, accumulate in enormous thicknesses 

 in certain depths of the oceans, which are a kind 

 of shallow basin of very large diameter, to which 

 Dana has applied the name of geo-synclinals. The 

 bottom of these vast depressions must present two 

 necessary conditions : (1) it must not be too far off 



