268 The Origin and Mode of Formation of the Vale of Wardour. 
on hills, where ice has dropped them, such as we see in Scotland or 
the Lake District, or in Wales. 
But, although we have no relics of zce action, our valley may have 
had, at the time when glacial conditions were vigorous further 
north, a more rapid erosion than ordinarily from the melting of the 
deep beds of snow which must then have fallen here, on the margin of 
an ice-covered country. For consider what the condition of the vale 
was in the Glacial Period. Our river, with its tributaries, had 
already worn down considerably into the plain formed by the marine 
denudation,and small escarpments of Green Sand and Chalk had begun 
to stand out, and hill and dale had begun to be formed; in short, 
the outline, in miniature, of our present scenery. Then there came 
that very cold period during which time, if we were not covered 
with ice, we certainly had heavy falls of snow, and frost-bound 
ground. Each spring that deep snow probably melted, and perhaps 
very suddenly, when a large volume of water—none of which could 
sink into the ground, because it was frozen hard—soon overfilled 
the water-courses, and carried away more material, and produced 
more erosion in a few hours than could be effected in quieter times 
in a century ! 
Indeed, we have evidence for such floods in the thick beds of brick 
earth at Fisherton and Bemerton, which contain the relics of an 
Arctic fauna. These brick earths were tranquilly deposited there, 
where the stream slackened, after being swept down by the sudden 
melting of the deep snows on Salisbury Plain and the country 
to the west. 
We see that great effects can arise from comparatively small yet 
ever active agents! The material which once filled this whole 
valley carried away to the sea! And this not by some one over- 
whelming flood, not by powerful glacial action, but by the gentle 
ever-continuous influence of small agents—chemical force, rain, and 
rivers ! 
The length of time which these atmospheric agencies have taken 
to erode this Vale of Wardour I would not be presumptuous enough 
to fix, or even to guess at ; geological periods are not to be measured 
by the petty scale of human chronology. But, long ago as it may 
—— 
