125 
NOTES ON SOME OF THE LIMESTONES OF 
CUMBERLAND AND WESTMORLAND. 
By J. G. GOODCHILD, H. M. Grout. Survey, F.G.S., &c. 
( The substance of a Lecture given at the Maryport 
Annual Meeting, August, 1891.) 
THE principal modes of formation of limestones in general were 
reviewed, with especial reference to the geological history of those 
occurring in Cumberland and Westmorland. Most of these lime- 
stones are of marine origin, and are due mainly to combined chemical 
action and the agency of organisms both animal and vegetable. 
The carbonates of lime set free as one of the results of atmospheric 
action upon various rocks containing calcium compounds, is carried 
by rivers towards the sea. At the zone of confluence of the river 
with the sea, most of the dissolved carbonate of lime is converted, 
by complex chemical reactions between the sea-water and that of 
the river, into sulphate and other salts of lime. In these forms it 
is widely diffused throughout ocean waters, and is thence asimi- 
lated by living organisms, which re-convert the various lime-salts 
into carbonate, in which form it constitutes greater part of the hard 
portions of their structure. On their death the organic carbonate 
of lime is left on the sea bottom as one of the chief constituents of 
limestone. But the ground mass, or paste, which, in all limestones, 
binds these organic constituents into compact rock, originates in a 
different manner. During the lifetime of marine organisms the 
diffusion of their own products of organic waste through the 
surrounding waters, of itself brings about chemical reaction upon 
