Correspondence—MUr. A. S. Eve. 479 
those of the deep Norwegian basin. The river-system is, on the 
whole, similar to that which now exists, and we may fairly infer 
that the building of the British Isles was completed. All we can 
say is, that there must have been good workmen in later Pliocene 
times; for if these views are correct, considerably more than half 
the physical features of the British Isles, both geographical and 
hydrographical, date from this limited interval of geologic time. 
In dealing with the final or Pleistocene stage, its abnormal climate, 
its submergences, and all the other enigmas of the Great Ice Age, 
the author avoids the extreme theories which find so much favour in 
some quarters. He allows that “the uncertainty which exists with 
regard to the real succession, and to the precise mode of formation 
of these Glacial deposits, makes it unsafe to attempt a geographical 
restoration of any of the several phases of the Glacial epoch.” He 
prefers to select for illustration the period in Pleistocene time when 
the rigour of the Ice Age had moderated, and when the British 
region had emerged from the waters of the Glacial Sea. The bed of 
the German Ocean is now so filled with débris that “the upheaval 
necessary to convert this sea into land after the Glacial period was 
100 fathoms less than would have been required to effect the same 
result in later Pliocene time.” An extension of the Rhine meanders 
through the great plain, to which the rivers of Eastern England are 
tributary. This represents the epoch when the coast-line of Western 
Europe coincided with the 80 fm. contour. Subsequently the water 
‘s on the land, these low-lying tracts are destroyed, and our 
eas are being cleaned out. The last great geographical touch 
was given when the tidal waters, assisted perhaps by depression, eat 
their way across the low water-shed of two river-valleys which is 
now marked by the Straits of Dover. 
We have followed Mr. Jukes-Browne with much pleasure through 
this very interesting study in geographical evolution, and can 
strongly recommend it to the attention of all geologists and physical 
geographers. In a case of this sort it is far easier to criticize than 
to construct, and no doubt each specialist could find something to 
suggest in every stage of the process from the earliest Paleeozoics to 
the latest Pleistocene times. Many points, also, in ancient geo- 
graphies must for ever remain mere matters of opinion. What is 
especially to be commended in this book is its freedom from any 
extravagant ideas: the author has taken for his motto, in medio tutis- 
simus ibis, and in this spirit has acted throughout.—W. H.H. 
CORRESPONDENCE. 
—— > —— 
NOTE ON A GLACIAL BED IN BEDFORDSHIRE. 
Srr,—The Lower Greensand forms a well-marked escarpment 
running parallel to that of the Chalk through Bedfordshire, and over- 
looking the flats consisting of Oxford and possibly Kimeridge Clay. 
About a mile from Ampthill in the direction of the ruined mansion 
at Houghton, quite on the edge of the escarpment, and facing the 
