106 
portion of the pebble bed, had probably a more local derivation; 
they are undoubtedly Oolitic, and differ from the matrix in 
which they are imbedded. They may therefore have been due 
to the breaking up of some of the previously consolidated 
Oolite, the debris of which was rolled along an Oolitic shore 
until it was deposited, in the form of pebbles with ferruginous 
sand and other detritus, derived from other disintegrated 
strata. 
At the close of the Limestone period a change took place, 
which led to the deposition of the Pea-grit. This deposit, as I 
have said, did not extend far beyond Selsley. The Freestone 
period followed, and the beds were formed apparently under 
similar conditions throughout the Cotteswold area; but the 
change which brought in the Oolitic Marl was limited in its 
operation to the north-east of Selsley, and the same remark 
applies to the conditions which induced the heaping up of shells 
which make the Gryphite Grit so fossiliferous at Stroud and 
Rodborough, and so sterile at Selsley. These variations of 
deposition support the probability that, after the deposit of 
the sands and part of the Lower Limestones, there was an 
elevation of the sea bottom, which led to the formation of 
the pebble beds; and this inequality of elevation, as com- 
pared with the northern Cotteswolds, was partially maintained 
during a considerable period, so that the Pea-grit and Oolite 
Marl deposits were restricted to the northern and middle 
divisions of the Cotteswolds, and the Gryphite was confined to 
the same area. These conditions become still more probable if 
we compare the Section of Leckhampton hill with Selsley, as in 
the following table :— 
TLeckbemnton Fee 2 
t. ins. . ans, 
Ragstone series, including the Clypeus, Trigonia and 
Gryphite’ Grits ae oa sce ee woe OO. 10) 0 Lome 
Upper Freestone “a oe ae nee 2. (28 O 15 0 
Oolite Marl mee of ace a Sus es Oa 1 6 
Freestone on wee ae i See woe L270" ee ae 
Pisolite beds om 38 0° 4 6 
Lower Limestone = 45 0 
The measurements of the Leckhampton Section are taken 
from the text of Professor Hull’s “Memoir of the Geological 
