JOWETT AND MUFF : GLACIATION OF BRADFORD, ETC. 203 
Some of the boulders are striated, and this drift probably in- 
•cludes the " scratched gravels " of authors. It is found almost 
exclusively to form mounds and moundy features, which are 
morainic in origin, and it might be styled " morainic drift." 
Moraines. — Lateral moraines are found on the hills, and 
terminal moraines of retrocession occur in the main valley. 
The latter are found at Tong Park, east of Baildon ; at Nab 
Wood, between Saltaire and Bingley ; and at Bingley. 
The Tong Park moraine consists of mounds, chiefly of 
gravel and fine sand. They extend along the floor of the valley 
on the north-west side of the Aire for about half a mile. 
*' Kettle-holes " are a common feature in the moraine. 
The moraine at Nab Wood, three-quarters of a mile west 
of Saltaire, is probably the finest in the district. It forms 
a concentric mound, stretching across the valley, with a steep 
concave slope 60 feet high facing up stream. The best section 
is at an old quarry 100 yards east of the " Seven Arches." Here, 
coarse gravelly drift, sometimes over 20 feet thick, rests on 
the Millstone Grit. The boulders are subangular or rounded, 
and are commonly between five inches and one foot in length. 
There is generally a clayey or loamy matrix, but hardly any 
trace of stratification. The surface of the moraine is irregular 
and moundy, and is strewn with large blocks of grit. 
Above the moraine is a stretch of alluvium, across which 
the river meanders. On reaching the moraine the river doubles 
back for a quarter of a mile, and escapes by a gorge cut through 
Millstone Grit at the northern end of the moraine. This is 
a very clear case of the so-called post-glacial diversion. It is 
very probable, however, that the gap had been opened and 
cut down to some extent before the ice-front had actually left 
the moraine. 
Bingley stands on a group of drift mounds which choke 
up the vaUey for over a mile. The river flows through a deep 
and narrow channel cut along the south-west margin of the 
mounds. Sections opened for laying drains near Myrtle Park 
showed a very coarse boulder drift, rarely with a clayey matrix. 
The top six feet of the deposit had been turned over, and the 
limestone boulders picked out for lime-burning. The mounds 
