372 
ON DIFFERENTIAL EARTH-MOVEMENTS DURING CARBONIFEROUS 
TIMES, AND THEIR SIGNIFICANCE AS FACTORS IN 
DETERMINING THE LIMITS OF THE YORKSHIRE, DERBYSHIRE, 
AND NOTTINGHAMSHIRE COALFIELD. 
BY COSMO JOHNS, M.I.MECH.E., F.G.S. 
(The substance of this paper was the subject of the introduction 
to a discussion on " Earth Movements " at the Leeds Meeting 
of the Yorkshire Geological Society, March 2nd, 1905. It 
has since been revised.) 
Contents. 
I. — Introduction. 
II.— The pre -Carboniferous Floor under Stress. 
in. — Datum Lines from which to Measure Vertical Move- 
ments. 
Significance of the Thinning of the Coal Measures 
towards their Margins. 
Character of the Faulting. 
Relative Age of the Charnian and Market Weighton 
Axes. 
VII. — The Age of the Pennine Range. 
VIII . — Conclusions . 
I. — Introduction. 
The theory generally accepted as explaining the occur- 
rence of Coal Measures in detached basins is that after the 
deposition of these rocks a series of earth movements, post- 
Carboniferous in time, took place, certain ridges were upheaved, 
and after these had suffered denudation the remaining portions 
of the Coal Measures would surv^ive in the basin-Hke depressions 
formed by the uphea\ed margins. Of late years, however, 
evidence has been accumulating which seems to suggest that 
IV.— 
v.— 
VI.— 
