80 
Table of the moreimportant Igneous Rocks, Strata, and 
other Deposits of South Devon. 
NS Igneous Rocks, upheaved at different 
GRANITE, |periods. They existed probably in a some- 
SERPENTINE, earth prior to their elevation, and it is also 
SCHORL ROCK, | |rational to think, that some portion of them 
HORNBLENDE,) oF their modifications, have had their pre- 
sent elevation from some more ancient era, 
jor even ab initio. This class of rocks is 
termed by many geologists “ Primitive 
Formations.” 
what similar form in the interior of the 
AND OTHER 
TRAPP ROCKS. 
Rocks of the Transition or Greywacke 
group, and so far as the south-west of Devon 
is concerned, apparently coevally deposited. 
The source of the substances of which they 
SLATE, are constituted is very problematical, but, 
though the immediate derivation from prior 
SANDSTONE. | existing rocks is questionable in respect of 
the lime and slate, it is hardly so in regard 
of the sandstones. 
LIME, 
> Substances formed or removed to their 
CLAY. present sites apparently by the passage of 
a vast current of water over the land, but, 
haying no solidifying power on the disin- 
OF FRAGMENTS tegrated particles, orsevered and transported 
ACCUMULATIONS \ | 
OF ROCK, jportions of rock, The clay may possibly 
PEBBLES, shave been derived from the argillaceous 
SAND, &C. formations previously existing. Aggregately 
these substances are called “ Diluvium.” 
I have omitted the mention of gneiss, porphyry, 
greywacké rock, and various other modifications of 
the above characteristic or typical strata, these 
being considered elsewhere. In the above table 
also, I have not included the sandstones and con- 
glomerates of the south-east of Devon, respecting 
the formation of which, there appears some peculi- 
arity, and to which perhaps the above remarks do 
not apply. 
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