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possibly accompanied by hail. On the surface of these layers of 
clay there are also impressions of the feet of small animals, which 
appear to have passed over the clay either during the showers or not 
long before, as the footsteps are indented by the drops of rain, but 
to a less degree than the untrodden parts, in consequence, the author 
conceives, of the pressure which the clay had undergone beneath the 
feet of the animals. Ripple marks are exhibited also on the surface of 
many sandstone strata in the same quarries; and the rain marks as 
well as the sharpness of many of the footsteps prove, that the clay was 
not covered by water during the shower, or while traversed by the 
animals; and Mr. Cunningham, therefore, is of opinion that the con- 
ditions necessary to the preservation of such impressions, particu- 
larly of the rain drops, would be a return of water over surfaces 
which had been left uncovered during an interval too short for the 
desiccation of the laminz of clay before the shower fell; and which 
were sufficiently soft to receive the impressions, as well as tenacious 
enough to retain them, until the return of the water which filled the 
prints with sand. Another condition is, that the velocity of the 
water charged with the sand was not sufficient to overcome the 
tenacity of the clay, or disturb the impressions of the rain drops. The 
author adds, that Dr. Buckland has suggested to him, that the interyal 
between the rise and fall of tides over extensive sandbanks, the sur- 
face of which was between the level of high and low water, might 
have afforded daily occasions for the fulfilment of all the conditions ; 
and that it is not easy to explain the alternate exposure to air and 
submersion under water without appealing to the flux and reflux of © 
tides. 
An extract was then read from a letter addressed to Dr. Buckland, 
by John Taylor, jun., Esq., F.G.S., on a slab of sandstone, exhibit- 
ing footmarks, and supposed to be from the Kelsall quarry, at the 
foot of Delamere Forest, but now in a pavement in the house of Mr. 
Potts, of Chester. 
A letter was next read, addressed to Dr. Buckland by Sir Philip 
Grey Egerton, Bart., M.P., F.G.S., respecting the same slab; and 
accompanied by a tracing of the foot-marks, by Miss Potts. 
When the slab was first laid down, there were no indications of the 
footsteps, and Sir Philip Egerton explains, in the following manner, 
their origin in a homogeneous stone and subsequent development, 
The weight of the animal on the soft sand compressed the yielding 
materials in the vicinity of the foot, and the print having been 
filled with sand, the stone, on becoming indurated, would present a 
nearly uniform texture. The action of the weather, on the flag 
being exposed, would remove the softer portions of the surface, and 
the denser parts surrounding the impressions of the feet, would resist 
the same operation, and present in relief the outline of the foot. 
The flag contains the prints of three hind and two fore feet, the 
latter bearing nearly the same proportions to the former as in the 
other, species, but Sir Philip Egerton could not make accurate 
