31 
stream from Goathland Dale, upon which is the waterfall called Thomas- 
son’s Force. Below Sleights the hills decrease in altitude, and the valley 
expands after its junction with Iburndale. Near Ruswarp the river curves 
slightly towards the north, and is joined by Cockmill Beck, and soon after- 
wards falls into the sea at Whitby. From Robin Hood’s Bay to Saltburn, 
the coast is margined by a series of elevated cliffs, which rise near Boulby 
to an elevation of 681 feet. Near Staiths is the mouth of a small stream, 
of which the two principal branches rise on the northern slope of Danby 
Beacon. Another rivulet rises near Freeburgh Hill, and falls into the sea 
at Skinningrove. A more considerable beck rises below the recently dis- 
covered station for Gyperus fuscus, at the head of Sleddale, and flows past 
Guisborough and Skelton to Saltburn. From Saltburn to Marske the 
coast is guarded by a series of bold rocky embankments, gradually des- 
cending northward into a range of loose sand-hills, firmly bound together 
by the interlacing roots of Ammophila arundinacea and Triticum junceum. 
Surface. — North of the Esk, from Roseberry Topping and Guisborough 
Moor, the hills slope gradually eastward, so that only the western ridge 
and a few detached summits attain the middle zone. The watershed on 
the south of the river declines in the same direction, from Burton Head 
(1485 feet) along Farndale Head (1412 feet), Shunnor Hoe (1404 feet), and 
Lilia Cross (1000). The remainder of the surface belongs to the lower 
zone. 
Structure. — The moorlands, both north and south of the Esk, consist of 
strata belonging to the Lower Oolite formation. Beneath these extend the 
shales and ironstones of the lias period, filling up the lower levels of the 
dales, and composing the whole of the cliffs at many parts of the coast. 
No. III.— DERWENT. 
Drainage. — South of Robin Hood’s Bay, the cliffs which margin the 
coast attain their highest elevation in High Peak (585 feet), and then 
descend gradually towards Scarborough and Filey. At Scalby is the 
mouth of a small stream about five miles in length, which runs past 
Cloughton and Burniston. The Derwent rises only three miles from the 
coast, about midway between Whitby and Scarborough. At first, it flows 
southward, down Harewooddale, Longdale, and the valley of Hackness, 
