A HISTORY OF CUMBERLAND 
land. As we trace these Upper Old Red conglomerates towards Shap, 
we find the same evidence continued, with the addition that, near Shap, 
fragments of the Shap Granite itself set in, and may be readily gathered 
from these rocks. 
The full significance of the fact just mentioned may be realized 
when it is remembered that such a rock as the Shap Granite could have 
been found only at a great depth below the surface, which depth may 
well be stated as several miles. In order, therefore, that a rock found 
at such a depth should make its appearance at the surface, there must be 
an upheaval equal to at least that extent, and the overlying thickness of 
rock must have been totally removed. This waste usually takes place pari 
passé with the upheaval. At the present day the rate of the removal of 
similar rock can hardly exceed one foot in about 4,000 years, and may 
be at as slow a rate as one in 6,000. But, if we set the rate at the time 
under consideration at one foot in three thousand years, it will be evident 
that the time required must extend to a great many millions of years. 
And yet all this took place after the period when the Old Red Sand- 
stone volcanoes had ceased to erupt, and prior to the commencement of 
the deposition of the Upper Old Red! As an additional fact of the 
same nature it may be mentioned that the aggregate thickness of the 
strata across whose edges in the Lake district the Upper Old Red un- 
conformably lies exceeds five miles. That is to say, before the Upper Old 
Red was laid down, an aggregate thickness of five miles of rock, mostly 
of a very durable nature, had been slowly and gradually swept away 
from this area. 
(7) The Life of the Upper Old Red Sandstone——The rock under 
notice having been formed under desert conditions, might be expected 
to be, as it actually is, without traces of life. Evidence obtained else- 
where, however, shows that under favourable conditions marine life 
flourished. In the rivers, and perhaps also in the inland lakes, there still 
remained some of the wonderful fishes which characterized the Cale- 
donian Old Red Sandstone, but nearly all of them are of different species 
—the long lapse of time since the commencement of the older period, 
added to the equally long time represented by the great unconformity, 
having sufficed for the gradual evolution of many new forms and the 
consequent extinction of those of the older types. _ 
(4) A very long period of time is implied by the vast unconformity 
which followed the Silurian Period and preceded the formation of the 
rocks of Devonian age. To that there must be added the time required 
for the formation of the Old Red Sandstone itself. If, instead of using 
these data in computing the time required, we base this estimate upon | 
the rate of formation of the marine limestones formed elsewhere during 
the period under consideration (assuming that rate to be one foot in 
25,000 years), we arrive at a total of 250,000,000 years for the period 
between the close of the Silurian Period and the commencement of Car- 
boniferous times. 
V. CargonireRous Psrtop.—(2) With the deposition of the 
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