Thos. Belt — The Glacial Period in Norfolk. 
157 
north-west, as we know tliat it was of immense tkickness in 
Lancaskire. 1 
Now if tke brick-earths liad been deposited before tke ice reached 
the coast, it seems not improbable tkat tkey skould be contorted by 
it and pusked up by tke risingice, so tkat in some cases tke tili would 
be actually deposited below tkem. We find that the ice kas certainly 
accomplisked tkis witk tke Lias, tke Kimmeridge-clay, and tke 
Ckalk, so that great masses of tkem are often found lying on tili ; 
and at tke Ely Clay-pit tkere was a fine section open last summer, 
skowing highly inclined beds of Ckalk, Kimmeridge Clay, and 
Neocomian Sands, all underlain by tili, and tkat by crushed and 
disturbed beds of Kimmeridge-clay. 
Evidence of tke passage of ice over tke district kas been found by 
Messrs. Wood and Harmer in tke valley of the Yare, tke Wensum, 
and tke Little Ouse, and I kave noticed it besides in tke valleys of 
tke Waveney and tke Ouse. 
I believe it was Mr. Croll wko fh’st pointed out tkat tke bed of the 
North Sea between Scotland and Scandinavia kad been filled witk 
ice, and tkis opinion is now held by many geologists. In a letter.to 
Nature in 1874, I remarked tkat, as up to tke time of the Glacial 
period tke Straits of Dover did not appear to have been cut through, 
it was evident tkat as soon as the nortkern end of tke German Ocean 
was blocked up by ice, a lake must kave been formed, wkick drained 
to the south-west, and gradually wore out a passage through tke 
Straits of Dover. Tkis kas appeared to many a rask speculation ; 
but if any one will take tke trouble to imagine what would be 
tke necessary result of stopping the flow of water to the north, 
before tke passage to tke English Channel was open, he will find 
tkat tke theory is not an improbable one ; and I am glad to see tkat 
it has been indorsed by Mr. Croll. 2 
At first, wken tke nortkern outlet was only partially obstructed, 
tke water would still be salt, thougk not so muck so as tke open sea, 
and perkaps only stand a few feet above the present sea-level ; but 
as the ice advanced, the water would rise until it overflowed tke 
istkmus that tken connected England witk tke Continent. Tke 
water of the lake would be fresk, or but slightly brackish, and I 
suppose it was tken tkat tke laminated brick-earths, including tkose 
of the lower part of the Tkames Valley, were deposited. Tke Straits 
of Dover were gradually cut through, and the brick-earths denuded, 
wkilst tke ice from the north was slowly advancing southward. At 
last, I suppose, tke ice reached the coast of Norfolk, forced up great 
masses of Ckalk, and contorted and skifted tke laminated brick- 
earths. 
A branch of tke ice-stream flowed up the Wask, and being re- 
inforced, as before mentioned, from the north-west, reached certainly 
as far soutk as Ely, and probably much furtker, sending off a branch 
along the depression now occupied by the valley of the Little Ouse 
and the Waveney. I suppose tkat the ice in passing along tke sea- 
1 5fr. R. H. Tiddeman, Quart. Journ. Geol. Soc. vol. xxviii. p. 471. 
2 Climate and Time, p. 452. 
