rROCEEDINGS OF GEOLOGICAL SOCIETIES. 
455 
November 7, 18G0. 
1. "Ou the Demidatiou of Soft Strata." By the Rev. 0 Fisher, M.A., 
P.G.S. 
The author first described tlie general features of the north-eastern portion 
of Essex, with tlie tablc-Luuls of gravel, clay valleys, and tidal rivers. The 
present conliguration of the district cannot be due, in t'iic autiior's opinion, to 
the action of sucii causes as we sec now in operation on the coast, combined 
with a slow elevation of the land. As a rule, the sea waves cannot excavate 
long narrow islets in horizontal and homogeneous beds, such as the gravel and 
clay of the district xiudcr notice, but give rise to long, approximately straight 
lines of cliif. The rounded sides of tiie Essex valleys seem to show they were 
not formed by wave-action ; nor are there any evidence of shingle-beds at the 
foot of the hills. Mr. Fisher believes that the surface of this district, and that 
of many other districts composed of yielding strata, must have been formed by 
a superincumbent mass of water drained off from a flat or sliglitly dome-shaped 
area. Sliglit dcj)ressious, cracks, or lines of readily yielding materials would 
determine the drainage-streams as the water retreated ; and these channels would 
be more or less scoured out according to the velocity of the water. Where the 
gravel covering of such a district was cut througli, the clay beneath would be 
channelled with a narrower valley ; and where the gravel was wholly leraoved, 
the valleys would be wider and the intermediate high ground rounded instead 
of being flat to))ped, just as is represented in those parts of the district where 
the clay composes the surface.* Similar appearances may be seen on a small 
scale in the mud of a tidal river. Tidal action, however, is not, according to 
the author, calculated to excavate narrow valleys in horizontal beds. 
Mr. Fisher suggests that the land must have been elevated by a sudden 
movement sufBcicnt to have caused a rush of v.'ater from the raised portions to 
seek a lower level, — either the land he'nig raised high and dry at once, or the 
sea-bottom raised to a higher level, though stiU remaining beneatli water. Suclr 
an elevation might be repeated again and again, with intervals of submergence; 
and such conditions appear to have obtained in Norfolk as well as in Essex. 
The author states that, in his opinion, escarpments, such as are so common 
among the secondary and tertiary beds, are rarely old clifl's, and their often 
rounded forms must be due to agencies similar to those which have produced 
the valleys of Essex. In some deep gorges of the Chalk near Dorchester the 
author has seen flints and great blocks of Tertiary puddingstone so arranged as 
to leave little doubt of their having been left by violent currents of water The 
position of the Marlborough " Weathers" is also attributed by the author to 
torrential action. 
Brick-earth is in part referred by Mr. Fisher to the deposition of sediment 
from turbid waters ; but also in great part to the unlading of icebergs. 
With regard to the manner in which the uprising of the land, which brought 
about these aqueous cataclysms, has been effected — whether by one slow and 
continued movement, or by one or more sudden movements, or by a mixed 
succession of these, the author argued that a slow and gradual elevation is not 
in accordance with the contour of the cxistmg surface of oui- softer strata ; that 
the elevation of the land previous to the period of the great-mammalian fauna, 
when its present contour was mainly given, was not gradual ; and that, after 
subsccpient depressions, there have been sudden depressions since that period. 
Lastly, it was pointed out that sudden vertical movements of the surface on 
a grand scale are of as probable occurrence as those lesser movements with 
which we are historically acquainted, because, botli in the case of strata pre- 
* Compare with Mr. Frere's remarks in tUe " Archteologia :" 1797. Ed, Geol, 
