File:The Quarterly journal of the Geological Society of London (12960246593).jpg

TKUNKS IN QCATERXART SANDS AT READING.
297
unworn and have sharp
edges ; they must have been
transported by floating ice-
blocks and so have escaped
rolling. Plint casts of A^i-
anchytes and Galerites are
tolerably common ; and one
good example of a Yentri-
culite was found. Of the
more perishable constituents
of the Chalk, a few rounded
nodules of hard chalk and
a worn fragment of Ino-
ceramus-sh.e\l were found.
(/3) Tertiaries. There is
a considerable proportion of
rounded flints derived from
the destruction of these
beds. A fair specimen of
Ostrea hellovacina from the
same source was also found,
(y) High-level gravels.
There occurs, thinly scat-
tered through all parts of
the gravel, a small propor-
tion of rounded quartzite
masses derived from the
waste of the high-level gra-
vels that once formed an
uninterrupted layer across
the then un excavated valley.
(3) Occasional elements
transported from a distance.
Worn fragments of Ostrea
(chiefly 0. dilaiata) occur ;
and one worn Nerincea was
found from the Oolites near
Oxford. A small piece of
blue, flssile limestone, when
broken, showed the charac-
teristic structure of Forest Marble. This must have been carried
41 miles if derived from the nearest source, Islip on the river
Ray, and if it followed the general direction of the river-valley
without taking the sinuous curves of a river.
This description holds good for all the gravels of the four faces of
the pit. The west and north are still well seen ; the east and south
are now entirely covered up.
B. The reconstructed beds, about 9 feet thick. These consist of Tertiary
elements (Woolwich and Beading beds, and to some extent the basement
Q.J.G.S. No. 142. X
.