59 
CHAPTER V. 
ST. EKTH BEDS. 
The only remaining deposit of Older Pliocene date that has yet 
been discovered in Britain is a small outlier, occupying a few 
acres, close to the village of St. Erth in Cornwall. St. Erth 
lies in the valley, formerly in all probability a strait, that divides 
the high land of the western part of Cornwall from the rest of the 
county. This valley connects Mounts Bay with St. Ives Bay, and 
only reaches 80 feet above the present level of the sea on the low 
watershed which divides the northward from the southward flowino; 
streams. 
Between the village of St. l^lrth and the Vicarage, which lies 
about a quarter of a mile to the east, there are some gently sloping 
fields, in which pits have been opened for sand, and to obtain clay 
for puddling for some engineering works at Penzance. Nothing 
would have been known about the fossiliferous deposit if it had 
not been for the economic value of the clay, which led to the 
deepening of the largest of the pits, so that the underlying un¬ 
weathered shelly clay was reached. Everywhere the angular 
rubbly deposit known in the west of England as Head overlaps 
the clay, so that without artificial sections we should not have 
suspected the presence of anything between the Head and the 
palaeozoic rocks. This widespread and deep deposit of Head 
makes it impossible to trace the exact limits of the clay, but 
the outcrop of slate and elvan at several points in the neighbour¬ 
hood shows that the basin must be of limited extent, probablv 
less than a quarter of a square mile, certainly under one square 
mile. 
The pit in question lies close to the Vicarage on the north¬ 
west side, and occupies a field sloping towards the north-west. 
The beds exposed in it, as far as can be seen, dip in the same 
direction, but at a higher angle, so that the clay thins out alto¬ 
gether towards the Vicarage, and it is not improbable that the 
Vicarage bdildings may rest almost directly on the solid rock. 
The sections constantly vary as the faces of the pit are cut 
back, and they may now be much altered, as the clay has been 
extensively dug since my visit in 1886. At that time heavy rains 
had somewhat obscured the lower part of the section, but the 
north-east face showed :— 
Feet. 
Angular Head - 
Head and clay mixed - 
Mottled clay - - - 
Blue shelly clay (base not seen) 
8 
2 
6 
