18 SOILS AND SPECIES, 
In the neighbourhood of Ashbourne the Keuper is overlaid 
with some extensive glacial deposits. These, which in some parts 
are as much as 50 feet in depth, occur between Yeldersley and 
Bradley on the east, and Ashbourne and Clifton on the west, 
and over a tract north and south between Alkmonton and above 
Edlaston. There are found here and there deposits of gravel, 
beds of micaceous gritstone, tile clay, and gypsum. There is a 
small patch of Yoredale rocks at Wild Park, Brailsford, and 
north-west of Mackworth Church. 
The broken character of the surface, geologically, is largely 
caused by the numerous faults which occur, rendering the assign- 
ment of districts to Bunter and Keuper respectively impracticable, 
and the threefold division adopted is consequently somewhat 
artificial. Still, from a climatic point of view, the area designated 
TI., viz., all west of a line drawn from Derby southward to 
Swarkeston, with the exception of the villages Swarkeston, 
Barrow, Twyford, Willington, and Egginton, lies at a higher 
average elevation, and is colder than the other two divisions, 
and is marked by the absence (except on its eastern borders) of 
such plants as Bryonia, Dipsacus silvestris, Hottona, Festuca 
Myurus. 
The division designated T2, and a decidedly warmer one than 
the last, being the area east of Derby and north of the Trent, 
reaches the lowest level 80-90 feet by the Trent near Long Eaton, 
rising to 412 feet above Locko Park. Its surface is in part 
alluvial, a broad tract south of Derby containing the ancient and 
present beds of the Derwent, and a strip on the north bank of 
the Trent from Shardlow to the County boundary. Of charac- 
teristic plants, owing to the restricted area, Samolus, Plantago 
Coronopus, Potamogeton flabellatus, alone occur. 
The remaining division, T3, viz., all south of the Trent, with 
Egginton Village, Willington, Twyford, Barrow, and Swarkeston, 
whilst mainly Trias, is, geologically, somewhat of a jumble, 
containing samples of every one of the formations hitherto 
noticed. Mountain limestone, Yoredale, grit, coal measures, 
Permian, Bunter, Keuper, are all represented. The Permian is 
