On the Pisolite and the Basement Beds of the Inferior Oolite of the 
Cotteswolds. By E. Wircenett, F.G.S. 
The deposits known as the “Pea Grit” or “ Pisolite,” are 
some of the most remarkable of the Oolitic series, and are 
peculiar to the Cotteswolds. 
The Pisolites are well known to Geologists, but to those who 
have not particularly observed them they may be described as 
flat or round: grains, varying in size from the 8th to the 3rd 
of an inch; the flat shape is the more prevalent, but many 
are elongated or round. es 
The deposit is of considerable thickness in the neighbourhood 
of Cheltenham. It becomes thinner at Birdlip, and gradually 
thins out westward of Stroud. 
The observations which I have to make upon this deposit are 
(1) as to the Structure and mode of formation of the Pisolites; 
and (2) the Stratigraphical range of the Beds. 
(1) The Pisolites are either concretionary structures or 
rounded fragments of Limestone, or, occasionally, of Coral. 
‘They are sometimes referred to as flattened grains, as if they 
had been compressed at the time they were deposited or before 
they became hardened. But although they are generally flat, 
there is nothing in their structure to indicate that those which 
are now flat were ever globular, but on the contrary, they have 
every appearance of having been formed very much in their 
present shape; in fact it will be found, on close examination, 
that the form of each Pisolite has been determined by that 
of its nucleus—those which are flat have flat substances for 
_ their nuclei, and those which are globular or elongated, have 
corresponding nuclei. In numerous instances the flat Pisolites 
have pieces of shell for their centres ; occasionally the Pisolite is 
merely a small univalve or a piece of coral coated over. In nearly 
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