S82 
SECOND REPORT— 1832 . 
solution of which we require the action of diluvial currents on 
the most vast and violent scale*. Trap dykes are so common 
in this district, and so frequently associated with the lines of 
fault, (see especially Mr. Wood s description of the great Stat- 
lick fault,) that we cannot but refer those dislocations princi¬ 
pally to volcanic agency. 
To proceed to the lower formations: The transition di¬ 
stricts f of our island, for a long period after the introduction of 
the more modern schools, were, as if in revenge for the exclu¬ 
sive attention devoted to the older rocks by the Wernerian 
school, abandoned to comparative neglect. These, however, 
have recently received important elucidation from the researches 
of Prof. Sedgwick, who has already fully described the trans¬ 
ition chains of the Cumbrian lake district, and is at present en¬ 
gaged in prosecuting a similar examination of North Wales ; 
while his friend Mr. Murchison is simultaneously exploring the 
junction of the transition and secondary districts along the 
Welsh border. In his description of the adjoining Island of 
Anglesea, Prof. Henslow had. already presented us with an 
Essay, which may well serve as a model of the manner in which 
such investigations ought to be conducted i. 
* On this subject I would quote an interesting note from Mr. Greenough’s 
“ Examination," p. 156. 
“Mr. Hutchinson, who wrote about 1750....of whose geological opinions I have 
more than once had occasion to speak with much respect....was the first by whom 
this important fact was noticed. His words are, 1 It is extremely rare to find a 
lifted edge of strata standing up above the general surface. The faults, however 
large the rise which they occasion, being rarely discernible by any sudden in¬ 
equality of the ground, numerous as cliffs, facades, mural ascents, or precipices are, 
very few of them are owing to faults; in general the matter has been carried off. 
Mr. Greenough gives other similar references to the works of Catcot, Wil¬ 
liams, Desmarest, Playfair, Deluc, Richardson, and Farev. 
f Here geology again stands in need of a term less barbarous than grauwacke 
slate, which would conveniently denominate the characteristic rock of thisaera. 
Might not clasmoschist (from the Greek x’hotQpci,') be conveniently adopted ? It 
would afford a term well contrasted to mica schist, the characteristic rock of 
the primitive group. We should thus obtain a series of convenient denomina¬ 
tions for the various geological groups which are principally distinguished: the 
primitive we might call the mica schistose group; the transition the clasmoschis- 
tose group; the denomination of the carboniferous group is already sufficiently 
established; for the new red sandstone with the associated magnesian zeclistein 
and rothe todte in its lower, and muschelkalk and keuper in its superior portion, 
I have already proposed the term, the poecilitic group. The oolitic group, for 
the lias and oolites; the cretaceous group, for the chalk and subjacent greensand ; 
and the supercretaceous group, for the tertiary formations, are appellations 
already commonly received. 
+ This Memoir, published in the first volume of the Cambridge Phil. Trans., 
is peculiarly valuable for its accurate description of the phsenomena of the nu¬ 
merous trap dykes, and the changes and crystallized minerals which they have 
produced in the rocks traversed by them. 
