O44 MR. P. F. KENDALL ON A SYSTEM OF [ Aug. 1902, 
such an ice-sheet asa postulate in post-Pliocene geology, than with 
the facts which have led so many to accept it as, with all its conse- 
quences, the only possible solution of the problem, will find an 
opportunity of examining this remarkable region. An easy way to 
see three of the great valleys, namely, Burn-Howe Dale, Blacksmith- 
Hill channel, and Evan-Howe Dale, is to take the coach from 
Scarborough to Whitby. Not only does the main road between the 
two towns cross these three valleys at their best parts, but it 
also traverses many fine overflow-channels in the country farther 
south. 
(b) Peak to Cloughton, and Hellwath to Harwood Dale 
and Burniston. 
The very complicated area now to be described extends from 
Jugger-Howe Beck to the country between the parallel of Peak on 
the north and the line of the Lindhead (Burniston) Beck on the 
south. The western and southern boundaries coincide closely with 
two great pre-Glacial valleys. The area thus enclosed is traversed by 
two streams flowing along ancient lines of drainage—Hayburn Beck 
and the nameless stream in Staintondale, which become confluent 
close to the sea at Hayburn Wyke: their respective valleys were the 
sites of glacier-lakes. (See map, Pl. XXVIT.) 
The area is extensively Drift-covered, especially near the coast and 
near the western boundary. Not even the highest prominences on 
the northern watershed appear to have entirely escaped glaciation. 
I have found, as before stated (p. 493), Drift-gravel with various 
erratics, including flint and Cheviot porphyrites, on the moorland 
near Green Dyke at about 825 feet above sea-level, and over Stony- 
Marl Howe. But Pye Rigg, only a mile farther south, appears to 
be Driftless, though my examination was restricted to the eastern 
and northern slopes and the summit, and I did not realize at the 
time that any special significance could attach to the observation. 
It seems certain that, for a short time at the period. of maximum 
extension, the ice reached the edge of what is now Jugger-Howe 
Beck. Whether the ice-margin was entire from Burn Howe to the 
confluence with Hellwath Burn, or whether it. swept in two lobes 
round Pye Rigg and Stony-Marl Howe, leaving an unglaciated 
area behind (that is, west of) the high ground, I am unable to say ; 
but the evidence is quite decisive that this condition quickly super- 
vened. I shall assume that the latter was the case, as for the 
purpose of the present discussion all the special phenomena belong 
to the stage of retreat. Before the Robin-Hood’s Bay watershed 
was breached by the overflow of Jugger-Howe Beck, a wide valley 
of normal type descended from Stony-Marl Moor along the Hellwath 
valley nearly to the site of its present junction with Jugger-Howe 
Beck ; thence, however, its course was continued down the Castle- 
Beck valley. 
When the ice advanced over the country, it thrust across this 
valley so as to impound the water, which in consequence took an 
