334
J. F. BLAKE AlfD W. H. HUDLESTON ON
wood, where they are cut through by the road. Here the oolites
are rather crystalline limestones towards the base, but become creamy,
close-grained, and thin-splitting further up, becoming, however, once
more crystalline and gritty as they change gradually through true
calcareous grits into yellow sandstones, the limestones having a shell-
bed towards the top. The yellow grits in their upper parts alternate
with hard blue rock and shelly beds, the equivalents of the Tri-
gonia-he&s of the Pickering quarries lying about 2 miles to the
south-west. Ascending the S.E. angle of Blansby-Park woods,
the Upper Limestones are partially revealed through the thick mat-
ting of undergrowth ; and, finally, the plateau at the top is found
to be held by an argillaceous form of Coral Rag. The thicknesses in
this very complete section are pretty nearly those already given, but
the supra-coralline beds are absent.
These latter, however, together with the Upper Limestones, and that
portion of the Middle Calcareous Grits which contain the Trigonia-he&s
are extensively quarried at Pickering. The following section (fig. 13)
is the result of a careful average of the quarries on both sides of the
valley as far as the workmen's cottages near the third quarry on the
west side. North of this the Coral Rag, which is barely recognizable
in the quarries nearest the town, begins to make a better figure.
Fig. 13. — Generalized Section at Pickering. (Scale 32 ft. to 1 inch.)
Upper Division
Middle Division. /
Coralline Oolite- \
Lower Division.
For details of the beds see table.fp. 335.