36 TORRS WARREN. 
Between the Torrs and Loch Ryan there is a low strath—a 
geological depression—as old possibly as Permian times (at 
least a strip of that formation exists along the west side of the 
loch, and in all likelihood extends under the Torrs, and may 
continue to a junction with the carboniferous rocks of Cumberland), 
and from the bits of coal got in the Torrs sands, this is rendered 
all the more likely. There are sand ridges in the Torrs parallel 
or nearly so to the present shore line, but some of them a mile 
from it, and even on the north border of the old sand hills there 
are remnants of ridges; and one would think that they ought to 
have been destroyed long ago. I offer the following suggestion 
as to the reason why ridges of sand may retain their original shape 
for a long time :—These ridges, I believe, having been originally 
along a shore line, when the wind blows sand up from the beach 
it also blows a lot of small shells and shell fragments, with 
immense quantities of ostracods and foraminifera, along with it, 
as well as bits of seaweed. This is shortly all bound together by 
the roots and stems of the marrum ; and although the shells may 
rot away by the percolation of acidulated water, the lime some- 
times gets deposited amongst the sand and will, no doubt, remain 
so, at least fora time. The ridges by and by get covered bya 
variety of plants, especially by the heaths, heather, brackens, silky 
willow, various grasses and flowering plants, including myriads of 
violets. They are now so firmly netted by plant roots that nothing 
but mechanical means, such as the burrowing of rabbits, of the 
repeated passage of cattle or carts over certain parts, will allow the 
wind to get into them, and when it does so it is difficult to stay 
its progress. Once it gets into a rabbit hole it soon scoops out a 
hollow, it may be from five to six feet in depth, sometimes in the 
shape of a nearly circular crater. The vegetation hangs dangling 
on the edge of the hole and gets so dried up that when it breaks 
off and slides down the slope it is generally quite dead, and seldom 
takes root again. These sand holes often increase to a great size, 
and sometimes get completely covered with vegetation. This is 
effected in the following way:—JIn very dry summers the wind 
scoops out the sand from the bottoms of the holes, and if these 
dry seasons are followed by wet ones, the sand in the bottoms of 
the holes becomes permanently damp, and seeds of plants blown 
into them take root. Once they gain a footing in the bottom of 
