112 
DEPOSITS OF THE LEEN VALLEY. 
of the valley. This Drift deposit was again met with close by in an 
excavation for a cistern 300ft. long, parallel with the gasholders. It 
was the same mixture of rusty brown and gray sand as before, decidedly 
contorted in places, and came to an end in the direction of the river 
just where the more recent alluvial deposits set in. 
The continuation, apparently, of the same deposit was also disclosed 
by a cutting made at the back of Springfield Bleach Works, at Old 
Basford, on the same side of the valley. The deposit of sand and 
pebbles, seen occupying a shelf cut out of the Lower Mottled Sand¬ 
stone at Spring Close, Lenton, twenty or thirty feet above the alluvial 
plain, is probably of this age. Here, too, there is evidence of the action 
of ice, for not only are the pebbles tightly wedged together in the 
sandy matrix in the most confused manner, but the surface of the 
underlying soft sand rock has been swept into small puckers in two or 
three instances by the pressure which produced corresponding flexures 
in the overlying gravel. It is not unlikely that the narrow strip of 
Drift that runs up the western margin of the alluvial flat at Bulwell 
belongs to this age, though, being rarely exposed, it is difficult to get 
any details of it, any more than that it is largely composed of the 
ground-up Permian limestone and marl on which it rests, and suddenly 
thickens where it occupies old hollows in the underlying rocks. The 
gravel that caps the low cliffs on the east side of the valley is probably 
also Glacial Drift. It consists of the usual varieties of quartz and 
quartzite, with flint chips, and a sandy matrix derived from the rock 
on which it rests. It is occasionally seen to occupy pre-existing 
hollows and ruts in the rock, is frequently contorted, and mostly very 
compact, being sometimes cemented by ferric oxide. No bones or 
other organic remains have been found in these ancient Glacial de¬ 
posits of the Leen, though mammalian bones have been met with in 
similar deposits in some other river valleys. 
The position of the Boulder Drift in the bottom of the Leen Valley 
shows that this valley, like most other river valleys in Britain, had 
been excavated to its present depth, and deeper, before the close of the 
Glacial Period. Besting partly on the Boulder Drift, and partly on a 
broad shelf of rock cut back out of the Bunter sandstone that forms 
the east side of the valley at Basford was some gravel distinct from 
either the modern river deposits on the one hand, or the Drift on the 
other. This gravel was about 5ft. thick, and passed up into five or six 
feet of loose, pebbly sand, that may have been washed down later. 
The deposit consisted of brown and yellow clean sand in obliquely- 
laminated patches, surrounded and interbedded with very short, 
irregular seams and “pockets” of pebbles. The oblique lamination and 
the confused arrangement of the pebbles in this deposit, all clearly 
due to the action of water alone, and not to that of ice, considered in 
connection with the position of this deposit on the side of the valley at 
a higher level than the later alluvial deposits, combine to suggest that 
this gravel is the “ tumultuous gravel” found occupying the sides of 
other river valleys m England and Scotland. It was formed when the 
