THE C0RALL1AN ROCKS OF ENGLAND.
371
This happens to to have been one of those places where the acci-
dents of distribution were favourable to the accumulation of shells.
Although no corals have been found, the general facies is interco-
ralline, and presents some analogies with the Urchin -beds of Grim-
ston presently to be described. Still it must be admitted that the
abundance of Ammonites in the bottom beds, especially 8, is an
exceptional feature in any portion of the Rag with which we are
acquainted ; but at the same time it is worthy of note that the cor-
date Ammonites quoted from here are of a very peculiar character,
and that the one called A. cawtonensis has some features in common
with A. alternans.
The character of the Rag of this portion of the district, west of
Slingsby, however, is of the more massive and Coralline type ; and
the quarries often afford really fine pictures (see fig. 21), where
the corals and shells and, above all, the spines of Gidaris flori-
gemma, larger here than anywhere else, weather out in handsome
arabesques. In the neighbourhood of Slingsby a change seems to be
coming on ; the division between, the Rag and the Coralline oolite is
for a while less pronounced.
Fig. 21. — Section in the Rag Quarry at Slingsby, showing Corals
in situ.
1. Coralline Oolite.
2. Coral Rag.
Proceeding eastwards from Slingsby towards Malton, the Coralline
oolite and yet lower beds occupy the country near the road, as
previously noted, and there is very little development of the usual
type of Rag to be seen hereabouts. Before crossing the Derwent
to inspect the last group of Corallian rocks, enclosed between its