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respectively of the schools of Neptunists and Plutonists. Werner 
and his school revived the old idea that the entire earth had been 
covered to the summits of the mountains by a universal ocean, 
and believed that from this ocean all the rocks had been deposited 
by chemical precipitation ; hence the geological formations were 
> universal in extent and uniform in character. At a suitable time 
this universal ocean conveniently disappeared but it had to be 
recalled in order to deposit some other formations which had 
been discovered out of their natural order. Then it again van- 
ished like a well trained servant. The Neptunists also insisted on 
the aqueous origin of the vast systems of rocks which are now 
known to be and many of which were then claimed by other in- 
vestigators to be of volcanic or igneous origin. 
On the other hand it was one of the fundamental doctrines 
of Hutton and the Plutonists that the internal heat of the globe 
has frequently forced great masses of molten rock into higher 
formations or onto the surface of the earth. However, Hutton 
realized that large bodies of rocks are of sedimentary origin. 
While Werner scouted the idea of The importance of earthquake 
and volcanic phenomena, Hutton saw in them and in their allied 
forces a sufficient agent for the tilting of the strata and the 
elevation of the dry lands above the oceans. Unlike his predeces- 
sors Hutton attributed volcanic activity to the internal heat of 
the globe rather than to the combustion of inflammable sub- 
stance, such as coal, bitumens, pyrite, &c. It was Hutton’s clear 
eye, too, which saw more than anyone before him had seen the 
importance of running water as a land sculptor. What we today 
accept as commonplace was by Hutton’s contemporaries rejected 
with scorn or quietly ignored. 
Previous to the early years of the 19th century geologists 
almost to a man had been Catastrophists — whether Diluvialists or 
Vulcanists — concerned in explaining all striking and unfamiliar 
phenomena, all well marked stages in earth history, by some 
great convulsion of Nature, by the intervention of some agent or 
force not now evident and of which modern science knows 
nothing. But Hutton taught that we have no right to appeal, in 
formulating the history of the earth, to any causes or forces 
which are not in operation at present. In other words the 
dominant idea in his philosophy was that the present is the key 
to the past. He thus laid the foundation for the school of Uni- 
