180 
MITCHELL : DRIFT DEPOSITS OF THE VALE OF MOWBRAY. 
and lepidodendron remains are often found. I have one specimen of 
the latter from a large tree. Great boulders of millstone grit are 
to be met with. The Yoredale series is plentifully represented, while 
the mountain limestone erratics are very common. These are fossili- 
ferous, containing encrinites, corals, and large producti. The Permian 
system is easily detected by pieces of magnesian limestone from the 
upper beds, and by a red breccia, called in some places brockram, 
which belongs to the lower part of the system. The lower Xew Red 
Sandstone is doubtless present, but this is not easily distinguished 
from that of the Trias. Permian fossils are scarce, but I have 
found Productus horridus. With regard to the Trias there is any 
amount of hunter sandstone, and I have found the typical fossil 
Ceratites nodosus. The Lias supplies many water rolled stones in 
which are fossil Gryph?eas, etc. ; also jet, lignite, and septaria. 
Pieces of Oolitic limestone are sometimes found, but not often. 
Thus the stones of the drift in the district which I have 
defined, are derived from every system from the Jurasic to the 
Cambrian inclusive, and probably from some earlier formations as 
well. I am unable to fix the age of the granites and trap rocks 
present, but the eruption which poured out the Shap granite, 
which is only to be found in situ, at Wastdale Crag and Wastdale 
Pyke in Westmoreland, occurred after the formation of the green 
slates, and before the deposition of the old red sandstones. Although 
all these different rocks are to be met with ,in a district ten miles 
square, some are found more plentifully in one part than in 
another. The Ure gravel on the west side contains more of the 
magnesian limestone, while the long ridge of rather elevated land 
which forms the water parting between the Ure and the Swale, and 
along which the old Roman Watling Street runs, has on both sides 
of it a tract of land which, though for the most part very fertile, 
contains gTeat quantities of erratics, interspersed in the soil for a 
considerable depth. Many of these are very large, and for the most 
part consist of sandstones, though many other rocks are to be found 
among them. Most of these are rounded, others are angular. 
Parallel to this ridge, but a few miles further east, a long range of 
sand and gravel hills folLjAvs the course of the Swale, sometimes on 
