918 PROFESSOR J. PRESTWICH ON THE EVIDENCES OF A SUBMERGENCE 
ago by the Rev. H. M, De La Condamine, gives what seems to me a very correct 
representation of a rubble-drift on a slope, covering the remnants of a raised beach. 
We have seen that after the deposition of the angular rabble the land on our 
Western Coasts was left considerably above the level at which it noAv stands, so 
that the land area was much enlarged. Such likewise appears to have been the case 
with the Channel Islands, which are fringed by submerged forests, like those rooted 
on the rubble-drift of Devon and Cornwall. On this surface, flint flakes and 
Neolithic implements, together with the remains of Deer, &c., are found, but no 
traces of Palseolithic Man have been discovered on or around the Islands. 
Brittany. —M. Ch. Barrois has shown* that in Finisterre, the coast is fringed 
in many places by Raised Beaches at a height of from 10 to 30 feet above the 
present beach, and he describes one in particular in the Bay of Kerguille, not far 
from Brest, which may be taken as a type of the rest. It lies against Silurian 
rocks and contains pebbles (elsewhere there are boulders) chiefly of Paleeozoic and 
Plutonic rocks, with numerous pebbles of white quartz and some chalk flints. M 
Barrois considers that the pebbles and boulders of these Raised Beaches are derived 
in part from the local rocks, whilst others, which comprise a great variety of 
jiorphyries, are from rocks in the hydrographical basins of the adjacent rivers, which 
include the Loire, and he attributes their transport to the action of coast and river 
ice at the commencement of the Quaternary period. 
I am not, however, satisfied that the drift of the shingle was altogether from that 
direction, for besides the pebbles of porphyry and of basalt foreign to the district, and 
which M. Barrois supposes may have come from the central plateau of France, 
there are upper chalk (Senonian) flints, showing a transport from the Coast of 
Picardy, or from the eastward, which would agree with that which then prevailed on 
the English coast. A current from the eastward would account also for the foreign 
boulders like those on the Sussex coast. Another point of resemblance between the 
French and English beaches, is the often enormous size of the pebbles, which form 
true boulder beaches. 
M. Barrois traces the extension of these beaches, and of pebble banks derived 
from them, along the coast of South Brittany. t M. Durocher;}; has also figured a 
well-marked Raised Beach, 12 to 15 feet above the sea level, but apparently without 
any overlying detrital matter, and without shells, at the mouth of the River Vilain. 
Thus far there can be no doubt of the synchronism of the land movements at the 
later Quaternary period, on both sides of the English Channel, but as we proceed 
further south, the breaks in the continuity of the beaches become longer, and the 
* ‘ Soc. Geol. dll Nord,’ toI. 4, p. 186, 1877. 
t A short notice by M. T. H:^na C. Rend.,’ p. 1870, 1874) indicates the presence of a Raised Beach 
and head on the shores of the Cotes dii Nord. 
J ‘ Bull. Soc. Geol. de France,’ 2® s&’., vol. 6, p. 212, 1849. 
