460 
some places by raised beaches or submerged forests. The evidence 
is, of course, chiefly inferential ; but the results of modern inquiry 
lead us to conclude that the earth’s crust is most unstable, that it 
is, ill fact, in a state of constant movement. The movements may 
be sudden when portions of the earth’s crust yield to an accumu- 
lation of pressure, or they may be slow when the pressure is 
gradual, and insufficient to cause a rupture. 
Earthquakes have been recorded from time to time as affecting 
Norfolk; but they do not appear to have been more than what 
Scrope termed “sensible vibratory undulations of the earth’s 
surface,” caused, perhaps, by shrinkage of rocks at a depth, and the 
intrusion of molten matter into the fissures. Our attention has 
recently been drawn to the subject of earth tremors, and the 
observations of Messrs. G. and H. Darwin, who have shown that our 
soil is liable to storms of microscopic earthquakes. f Mr. G. Darwin 
has also indicated that the rising and sinking of land may 
be influenced by barometric pressure. Other writers, amongst whom 
Dr. C. Eicketts, have suggested that upheaval and subsidence may 
be caused or assisted by denudation or deposition of materials, as 
well as by the great development of ice during the Glacial epoch, 
and its subsequent dissolution. Hence we see that the very 
sculpturing of our earth’s surface, in the formation of our scenery, 
may be one cause of those movements which we infer to have taken 
place from the character of our strata. 
As time passed on we come to the period when historical 
evidence first tells of some of the doings of man in this country — 
that marked by the writings of Cccsar. In his time the ancient 
Britons were so civilized as to have swords of iron, besides a 
coinage of their own. This Iron age, as it is called, extended 
backwards for 400 or 500 b.c. The earliest inhabitants in 
Neolithic times were, probably, of an Iberic type ; those who 
followed (generally known as the ancient Britons) were the Celts 
and Belgce. The after struggles, by which the Eoman and the 
Saxon successively overcame the Celt, and the conflicts of Saxon 
and Dane, are matters of history. The progress of civilization and 
* Rev. 0. Fisher, Quart Journ. Geol. Soc. vol. xvii. p. 4. 
Geol. Mag. dec. ii. vol ix. p. 481. 
