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NOTES ON THE STRATA AND DEPOSITION OF THE MILLSTONE GRITS. 
BY WILLIAM SIMPSON, F.G.S. 
In giving a paper upon this series of rocks, it is not my pur- 
pose so much to go into any detail, as to present, in as short a 
manner as possible, some of the broad facts of observation and 
generalization, and such deductions therefrom as may be useful to 
those of our members not so favourably situated for their personal 
study, or to those who, having confined their attention to the more 
commercially valuable Coal Measures, may still desire to have a fair 
theoretical acquaintance with this series, so intimately associated 
with, and immediately underlying, our lower coal-field. 
Without having anything new to offer, I have still endeavoured 
to gather together, in presentable form, a few threads of information 
scattered over various memoirs and works of reference, supplemented 
by some little personal observation and speculation. 
The Millstone Grits are not a particularly interesting series, and 
offer comparatively small inducement or reward to close investiga- 
tion. The sandstones, flags, and grits are extensively quarried. The 
occasional small beds of coal have in some places been worked, but 
are generally of no value ; and, save in one or two inconstant 
horizons, there is little to induce the fossil hunter to break the rock 
or part the shale. The Millstone Grit Beds, however, in their out- 
crop, cover a greater area in the West Biding than any other forma- 
tion, and, as marking a period of change from the quieter infilling of 
the Yoredale shales and sandstones, and the constant shoaling and 
swampy growths of the Coal Measures, they are worthy of our 
attention. 
Dividing and margining the important coal-fields of Stafford- 
shire, Lancashire, and Yorkshire, the beds of the series extend from 
the borders of Derbyshire and Cheshire along the course of the Pennine 
Chain, westward and northward. They occupy the summits of, and 
form outliers on, the high hills above the Mountain Limestone and Yore- 
dales, while eastward they stretch to the Permian Escarpment from 
