446 
“ Great Ice Age ” wliicli separates our present fauna and flora, for 
the most part, from the life whicli preceded it. 
It would be quite out of place here to attempt any detailed sketch 
of this period, to speculate on its causes, or try to picture the 
method of formation of its many kinds of deposit. So long as we 
treat the subject broadly we tread upon safe ground; the moment we 
enter into particulars we trespass into a region where our present 
knowledge forbids, although it does not prevent, very positive 
assertions. 
The deposits of this great Glacial period are most important in 
the history of our scenery, for the jDresent features are for the most 
part carved out of them, although in the river valleys and other 
places often deep enough to expose the earlier strata beneath. 
Nowhere are they better exhibited than in the cliff-sections between 
V\/ eybourn and Ilappisburgh ; and there we find almost every kind 
of sediment, from marl to boulder gravel, with the intermediate 
varieties of clay, loam, and sand. We may see in one place, as 
at Happisburgh, a stiff blue clay (Cromer Till) containing pebbles 
of chalk, many of them glaciated, and boulders of granite, 
greenstone, felstone, carboniferous limestone, and septaria, sometimes 
beautifully grooved and striated by ice-action. 
I hen, on the same coast, Ave have exhibited beds of brickearth 
and marl and sand (Contorted Drift), showing frequent and 
astounding disturbances. For the beds are twisted up at all angles, 
in zig-zag or S-shaped forms, noAV enclosing nests of sand Avith 
shells, or patches of marl ; and again containing those huge 
boulders of re-arranged chalk, or even little-disturbed chalk, 
that form some of the largest transported masses of rock to be 
Avitnessed in this country. 
Over a considerable portion of South Norfolk, north of Diss, 
around Tivetshall, Long Stratton, Brooke, Forncett, and Attle- 
borough, there occurs a tolerably uniform clay, containing chalk- 
stones, flints, and boulders. It is kuoAvn as the great Chalky 
Boulder Clay. 
T'hesc beds furnish unmistakable relies of times Avhen much of 
North Britain Avas enveloped in a mantle of ice, Avhich spread 
southAAmrds and eastAvards over the Avoids of Yorkshire and Lincoln- 
shire, bringing dibris of Chalk and Oolites and other rocks over 
the Eastern Counties. 
