Mrs. McKenny Hughes—Pleistocene Mollusca. 197 
those at Barnwell covering a large area near Shelford, where also 
Corbicula fluminalis is found, and extending by Trumpington to the 
well-marked terrace of Grantchester 
The Grantchester gravel (see Section Fig. 4) occurred in irregular 
masses troughed into the underlying Chalk-marl, and was exposed 
by the removal of the whole of the surface in the process of digging 
for phosphate nodules. It was not clear that it bore any relation to 
the existing geographical features; but its irregularity and the 
presence of pans of decomposed vegetable matter and of masses of 
shells buried in chalky loam, seemed to indicate accumulations along 
the shifting channels of a river wandering over a tolerably wide 
area, and deriving much of its material from older gravels, from 
Boulder-clay, and even directly from the Chalk-marl which it here 
and there touched in its course. All the shells in the Woodwardian 
Museum were obtained from one rich deposit of small extent close 
to the farm track, just beyond the §8.W. corner of the camp, at a 
depth of about 5 to 8 feet from the surface. This pit is now filled 
up, and although there are here and there openings from which sand 
and gravel are being dug, no shells have been found in them; nor 
are any beds now exposed exactly similar to those from which the 
shells were formerly obtained. The list of Mammalian remains and 
shells given in Column II. p. 202, has not hitherto been published. 
Beyond Grantchester, about four miles to the south-west, the 
village of Barrington stands on a terrace on the left bank of the 
River Rhee. This terrace consists principally of loam derived from 
the Chalk-marl with lines and lenticular beds of sand and gravel to 
a depth of from 5 to 10 feet. 
Fic. 5.—Section seen in pit north of Windmill, near Westgate Farm, Barrington. 
Scale—10 feet to 1 inch. 
Y, ME 4 > Sea 
LMT °° 
a, Surface soil. 1’—2'; b, Chalky loam and sand, with small lines and lenticular 
beds of gravel. At the southern or lower end of the digging the gravel and 
sand is looped into the top of the underlying Chalk-marl. 6’—7’ ; c, Chalk-marl ; 
d, Cambridge Greensand ; ¢, Gault. 
The gravel does not appear on the 1-inch Survey Map, probably 
because at the time that map was made there was nothing at the 
surface to distinguish the loam which belonged to the gravel from 
the decomposed surface of the marl, etc. In subsequent phosphate 
