MITCHELL : DRIFT DEPOSITS OF THE VALE OF MOWBRAY. 179 
deposits of brick clay ; also a sandy clay, which seems to contain 
some lime and iron, and in places forms an impermeable structure, 
which from its hardness seems to be fast turning into stone. It is 
called Moor-pan," because it underlies the peaty soil of some of 
the moors, and prevents the water draining away. Besides the 
boulders I have enumerated, there are to be found a great many speci- 
mens of schistose and metamorphic rocks. In one part pieces of 
lignite are plentiful, and some specimens of good jet can be found. 
Four, at least, different kinds of granite are met with, one of which is 
grey; another is red, not porphyritic, and without mica or hornblende. 
The commonest kind, found in many places as good-sized boulders, 
and in every gravel heap in smaller pieces, is the charcteristic Shap 
Granite. This is light-red, with large porphyritic crystals of pink 
felspar, also much mica and hornblende. The fourth kind is a 
brighter red in colour, also full of masses of felspar, but no mica 
is seen in it, hornblend is present but rather sparingly. Numerous 
specimens of Basic Igneous Rocks are met with, differing in colour 
from black to light-grey, and varying much in texture, some close- 
grained and comparatively smooth specimens of volcanic tufa 
occur, while others are ragged and course. I ought also to mention 
pieces of conglomerate and breccia which I have found at times. 
Septaria or cement stones are very common in some parts. Having 
recorded examples of the great variety of rocks which have been brought 
together in the drift, I shall refer some of them to the systems to 
which they originally belonged. With regard to the numerous schis- 
tose and metamorphic stones I am unable to say more than that 
probably they belong to some of the oldest sedimentary rocks. I 
think that we may safely consider that the pieces of green slate have 
been brought from the neighbourhood of Skiddaw, and are Cambrian. 
The Silurian system has supplied many of the erratics which can be 
identified by the fossils they contain, as tentaculites, annulatus, 
pentamerus, etc. I have found the old red sandstone fossil Parka 
decipiens, the remains of the spawn of a crustacean. There is an 
immense number of stones from the Carboniferous system in the 
drift. Sandstones from the upper coal measures are to be found 
everywhere with casts of stigmaria on them, sigillaria, calamites, 
