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ON THE NATURE, CORRELATION, AND MODE OF ACCUMULATION 
OF THE DRIFT-DEPOSITS OF THE WEST RIDING OF YORK- 
SHIRE ; WITH REMARKS ON THE ORIGIN OF ESCARPMENTS, 
VALLEYS, AND OUTLET-GORGES, AND AN APPENDIX ON 
THE CLIFFS OF PLUMPTON, BRIMHAM, GOREDALE, AND 
MALHAM. BY D. MACKINTOSH, F.G.S., ETC., AUTHOR OF 
"SCENERY OF ENGLAND AND WALES I ITS CHARACTER AND 
ORIGIN," AND PAPERS ON DRIFTS IN THE " QUART. JOURN. 
GEOL. SOC. OF LONDON." 
[i^or Plate and Explanation see Close of this Paper.} 
For the last six montlis I have been devoting almost undi- 
vided attention to the classification and correlation of the 
drifts of the West Riding, between York and Settle in one 
direction, and between Ripon and Barnsley in another. I 
started with the idea, which subsequent observations have 
confirmed, that it is only by a comparison of the characteris- 
tics of the drifts on plains with those in valleys and on hill 
sides that we can arrive at correct notions of the mode of 
their accumulation. 
CLASSIFICATION AND DESCRIPTION OF THE DRIFTS OF THE 
WEST RIDING. 
1. Greyish-blue and Variegated Boulder-Clay. — So far as 
I can ascertain, it is to the late Mr. Teale, of Leeds, that we 
are indebted for the discovery of two lower boulder clays, the 
blue and the yellow. He found patches of blue clay at New 
Wortley, Nether Green, Woodhouse Moor, Ad el, and Yeadon 
Colliery, at various levels, and at Adwalton at a height of 
about 600 feet above the sea. At nearly all these places he 
found the blue clay overlain by the yellow clay. I have 
traced the existence of blue clay up the valleys of the Aire 
and "Wharfe, and on the plain of Craven, where it is exten- 
sively developed. At lower levels, to the south-east and north 
