New Series.] 
[Paet II. 
PAPEES 
r.EAD BEFORE THE 
GEOLOGICAL AND POLTTECHMG SOCIETY 
1875. 
ON THE RED BEDS AT THE BASE OF THE CARBONIFEROrS 
LIMESTONE IN THE N.W. OF ENGLAND. BY CHARLES 
BIRD, B.A. ; SCIENCE MASTER IN THE BRADFORD GRAMMAR 
SCHOOL ; HONORARY SECRETARY TO THE BRADFORD PHILO- 
SOPHICAL SOCIETY. (plates IL AND IIl) 
Between tlie silurian and the carboniferous systems 
there occurs a great thickness of red and yellow sandstones 
and conglomerates, to which the name of old red sandstone 
has been given. These beds appear to have been deposited 
in shallow, brackish, or fresh waters, caused by the gradual 
shallowing and contracting of the silurian sea. The fossils 
of the upper silurian beds become fewer in number and 
dwarfed in form as they pass upwards and finally disappear, 
and all traces of marine shells die out, while land plants and 
fresh water fishes become the characteristic forms. 
The old red sandstone of Shropshire, Hereford, and Wales 
lies regularly and conformably upon the upper Ludlow rocks, 
and after attaining a thickness of 10,000 feet, passes upwards 
conformably and without any break into the carboniferous 
limestone. 
5 
