VIII.—Notes on some Observed Rates of Weathering of Limestones

Abstract

In the Geol. Mag. for July, 1875, p. 326, the writer of the present note gave some data bearing upon the rate of weathering of certain limestones of the Lower Carboniferous Series, deduced from the observed extent of waste that had affected some dated tombstones in Kirkby Stephen Churchyard. The series of observations of which that formed a part were suggested several years previously by the fact that many of the rough blocks of limestone used for walling in that neighbourhood had evidently suffered considerable waste since the erection of the walls, and this especially on the upper and outer surfaces of the stones referred to. In a few of these cases (as well as in many other cases observed since) it was perfectly evident that, since the coping stones had been placed in their present positions, the waste of the limestone by atmospheric causes had proceeded to at least as much as a quarter of an inch. This was evident from the fact that thin, delicate, fragments of Corals, Brachiopods, Encrinites, etc., were left standing out in sharp relief to that extent above the general surface of the adjoining limestone matrix.