5052 MR. P. F. KENDALL ON A SYSTEM OF [ Aug. 1902, 
Much moraine-gravel extends from here to Hollin Rigg, but no 
decisive evidence of lake-overflows is visible. At the southern angle 
of the escarpment at Scalby Nab a gravel-covered spur exists, of 
much smaller dimensions than the northern one, but, like it, scored 
on its outer (western) face by a small gully with a fall to the 
southward. 
(d) Scalby to Filey. 
The last tract of country to come within the scope of this 
paper is that which completes the system of extra-morainic drainage 
of the Cleveland District on its seaward side. It extends from 
Scalby to Filey along the coast, and inland from Mowthorpe at the 
top of Forge Valley to Wykeham in the Vale of Pickering. The 
physical features of the region are simple—there is a coastal tract 
of Middle Jurassic rocks backed by a bold escarpment of Corallian 
rocks, which sweeps round from Mowthorpe by way of Scarborough 
to Gristhorpe, where it reaches the coast and forms the fine range of 
cliffs terminating in the natural breakwater of Filey Brigg. 
The Corallian rocks dip in towards the Vale of Pickering, but the 
strike, which is nearly due east and west in the Forge Valley, 
swings round to a west-north-westerly and east-south-easterly 
direction near Filey, while in a westerly direction it changes 
in the opposite sense; the dip-slope is consequently arcuate. 
Many deep valleys exist in the Corallian rocks which are 
almost or quite destitute of streams at the present time. Such 
valleys may have been produced like those in the Carboniferous 
Limestone, by streams which have subsequently taken to under- 
ground channels; or again they may, like the great valleys in the 
Chalk Wolds, have been excavated by running water during the 
Glacial Period, when the rocks were all rendered impervious by their 
frozen condition. It has been necessary to discriminate carefully 
between these valleys and the abandoned lake-overtlows. The Drift- 
deposits attain a great thickness 1n the area (in one case noted by 
Mr. Fox-Strangways, probably as much as 200 feet) in the deeper 
pre-Glacial hollows. I have found it desirable in this investigation to 
examine very carefully the extension of the Glacial deposits at high 
levels on the Corallian rocks: it seems clear that they extend 
completely over the range from Scarborough to Filey. The great 
elevated block to the westward of Scarborough—Seamer and Irton 
Moors—opposed, however, so great an obstacle to the ice, that 
although the escarpment was overtopped even at its highest part, and 
gravelly moraine was laid down near the brink to form the irregular 
range of hills culminating in Seamer Beacon 600 feet above sea-level, 
yet ‘the western slope was never invaded. 
The edge of the ice here can be made out with great precision. 
Hagworm Hill is a mound of sand and gravel with erratic 
pebbles, and similar hills range southward to Riggs Head, but I 
searched in vain the cultivated land immediately to the westward 
for a foreign pebble—the soil appeared to be entirely the product of 
underlying rocks. 
