TRANSACTIONS OF SECTION C. 743 
the sandstone pipes the strie are deflected, and sweep round, till on its landward 
or 8.S.W. side they are running as much as 20°N. of W. This is on a convex 
surface of limestone, forming the side of a moat-like depression, about a foot wide 
at the top and the same deep, running round the mass of sandstone filling the pipe. 
A short distance away, a low face of limestone is not merely furrowed, but under- 
cut. It is smoothed and striated in the usual manner, and is undercut some two 
or three inches, the overhanging surface being as much as 15°, and in parts even 
30° from the vertical. It would seem that these effects must have been produced 
by an agent which moulded itself like a plastic body to the face of the rock. The 
ice-worn surfaces are overlaid by about ten feet of reddish boulder clay, poor in 
stones, 
6. On the Glacial Drainage of Yorkshire, By Percy F. Krunpatt, L£.G.S, 
The author referred to the effects produced when the edge of a glacier or ice- 
sheet obstructed the rivers of the adjacent country, ponding up the water to pro- 
duce a lake, whose overflow was carried over into some neighbouring valley as a 
river. Sometimes the overflow would cross the main watershed, while at other times 
it would pass into some minor valley of the same slope. In this way single lakes or 
chains of lakes are formed, discharging by valleys cutting across spurs and ridges. 
Where lakes of this description existed during the Glacial Period their traces may 
be left after the withdrawal of the ice in the form of beach lines, silt deposits, 
deltas of inflowing streams, and abandoned overflow channels. In the famous 
Glenroy lakes the beaches and deltas are the noticeable features, but in Yorkshire 
the author has relied chiefly upon the streamless river valleys marking the overflow, 
though other indications often exist. These valleys present marked features. They 
are deep, sharply cut, and the character of their windings shows that they were 
occupied by large rivers. Moreover they often trench flat plateaux, from which 
they received no commensurable tributaries, and cut completely through main 
watersheds or projecting spurs. 
The author describes the distribution of the ancient glaciers of Yorkshire, 
showing that while the Pennine Valleys were occupied by separate ice streams the 
Vale of York was covered by a great glacier. The edge of the Scandinavian ice- 
sheet abutted upon the whole coast line, and pressed against the northern face of 
the Cleveland Hills. The whole drainage of the district was obstructed, and Mr. 
Strangways long ago recognised that the Vale of Pickering was converted into a 
lake which drained backward across the natural watershed, which became trenched 
by the beautiful gorge of the Derwent at Castle Howard. The authov’s investiga- 
tions showed that Newtondale was the overflow of another great lake in Eskdale, 
but a lobe of the Scandinavian ice-sheet crossed the Cleveland watershed near 
Egton, and stood against the hills above Grosmont, which was severed by two 
streamless gorges forming a connection between the main lake and a lesser one at 
Goathland. Lalkelets fringed the edge of the ice along the outer face of the Cleve- 
land Hills from Swainby to Stonegate, and for the most part drained one into 
another until some overflow into Eskdale was encountered. As the ice shrank by 
the series of stages new channels were cut at lower level across the spurs, and in 
some cases water flowed round the end of a lobe of ice as it stood against the slope 
of the hills, and thus curious ‘in and out’ valleys were cut, as near Freeborough. 
Robin Hood’s Bay was drained by four successive outlets which cut through the 
amphitheatre of hills, and which are splendidly shown on the road from Scar- 
borough to Whitby. The beaches of the old lakes were seldom visible, for the 
outlets, being cut through very soft rocks, were lowered too rapidly for well-defined 
beaches to be formed, but gravel deltas, where the overflow of one lake entered the 
quiet waters of another, were of frequent occurrence, the largest being that on which 
the town of Pickering is built. The floor deposits of the lakes are also well seen, 
On the western side of the Vale of York, near Ripon, the features are somewhat 
different. The lateral moraine of a great glacier is clearly traceable extending 
from Kirkby Malzeard to Nidd Hall. As the glacier advanced the eastward-flowing 
streams were successively ponded up into lakes, which overflowed each into its 
