332 Reports and Proceedings—Geological Society of London. 
Rugby; the Irish Sea ice passed into the northern part of the basin 
of the Lower Severn; ice from the Brecknock Beacons passed towards 
the Bristol Channel and, combined with Irish Sea ice crossing 
Pembrokeshire from St. David’s Head towards Cardiff, may have 
caused the accumulation of sedentary ice in the Severn Valley. 
After considering the case of Lake Pickering and the Malton Gorge 
as a typical example, the author passes on to Lake Shrewsbury and 
the gorge at Ironbridge. Pre-Glacial drainage of the Upper Severn 
and Vyrnwy was probably northwards; when a Glacial lake was 
first formed over the Cheshire plain it may have drained towards the 
Trent, possibly by Rudyard and Madely; when these gaps were 
closed, the lowest outlet seems to have been towards the south, and 
the Severn Gorge at Ironbridge was cut. The canon of the Camlad 
at Chirbury, known as Marrington Dingle, appears to have been 
‘caused by outflow from a Church Stoke lake which was driven into 
the Ordovician ground to the north and east. Lake Trowbridge and 
the gorges of Clifton and Bradford-on-Avon are next dealt with, the 
latter being attributed to the overflow of a Glacial lake occupying 
the Trowbridge plain, and the former to the blocking of the Flax- 
Bourton valley by ice. ‘The gaps in the Jurassic escarpment at 
Lincoln and Ancaster are explained as overflows from a lake caused 
by the damming of the Trent outlet towards the Humber. This 
gave rise at first to the more northern, and later to the southern 
gorge. Finally, Lake Oxford and the Goring Gap are dealt with 
in considerable detail. Certain Drift-filled valleys are regarded as 
excavated by a river flowing from the south-west—the primeval 
Thames. The distribution of the Chalky Boulder-clay shows that 
the advance of the Great Eastern Glacier from the north-east must 
have arrested drainage flowing towards the Wash, and caused a lake 
which may possibly have first overflowed through the Newport valley 
into that of the Stort, or by the Hitchin valley into the Lea, or later 
into the Colne by the Leighton Buzzard valley. When the ice 
reached Buckingham, such channels were closed and the overflow 
must have taken place farther to the south-west, over what are now 
the Tring, Wendover, and Wycombe Gaps, and eventually by the 
Goring Gap itself. 
Gravels containing Triassic and drifted flint pebbles derived from 
Glacial deposits may be traced from Goring across the Oxford Plain, 
at an elevation of between 400 and 500 feet, into the Evenlode 
Valley, and thence into the basin of the Avon. Their occurrence on 
the higher slopes of the Goring cation indicate that the excavation 
of the latter did not commence until after the arrival of glacially 
derived detritus in the region in question; the Goring Gap is, 
therefore, of Glacial age. 
The author is unable to reconcile the views here given with those 
of Professor W. M. Davis on the valley erosion of Central England. | 
Any relation which may have existed between the present drainage 
system and that of some former period when a peneplain may have 
extended over the Jurassic and Cretaceous formations alike, and 
consequent rivers ran out to sea over it, is remote and impossible to 
trace. With the exception of the Goring gorge, which may be 
