The proofs of glaciation in the county
are abundant. Numerous instances of striations are met with, especially
in the volcanic area between Lochwinnoch and Port Glasgow. Throughout
that district the general trend of the ice-markings is SE, due to the
movement of the great ice sheet radiating from the Highland mountains.
This SE trend continues as far as Kilbarchan and Lochwinnoch, but to
the E of these localities the striae gradually swing round to the SW.
This change in the direction of the ice movement has been adequately
explained by Professor James Geikie,
who contends that during the great extension of the ice the glaciers
from the Highland mountains moved in an E direction along the valley of
the Clyde till they coalesced with those radiating from the Southern
Uplands. Eventually the combined ice sheets moved in a SW direction
across the volcanic chain in the E of Renfrewshire towards the Firth of
Clyde.
Economic Minerals.--Copper ore occurs in grey sandstone near Gourock, and several copper mines have been worked in the volcanic rocks near Lochwinnoch. Agates
occur in great abundance in the amygdaloidal volcanic rocks. The
various ironstones and coal seams already enumerated, both in the true Coal-measures and in the coal-bearing group of the Carboniferous Limestone, have been extensively wrought. The Arden
Limestone has been largely quarried near Barrhead and Thornliebank,
where it reaches a thickness of about 10 feet. The Orchard Limestone,
though comparatively thin, has been highly prized as a cement
limestone, owing to the valuable feature which it possesses of
`setting' under water. Alum has been largely manufactured from the
shale at Hurlet and at the Nitshill chemical works; copperas is
obtained from the iron pyrites in the shale. As already indicated the
great Oil-shale series of Midlothian is represented in this county by
contemporaneous volcanic rocks, but there is a band of oil shale
underneath the Hosie Limestone at various localities between Houston
and the E border of the county. The volcanic rocks supply excellent
road metal; and the Giffnock sandstones, as well as some of the beds of
limestone, supply excellent building material. See Geological Survey
Maps (1 inch) of Scotland, sheets 22 and 30, and the explanation to
sheet 22.
Soils and Agriculture.--The soil of the
hill districts is principally a light earth, overlying gravel or
disintegrated volcanic rock, and is in some parts covered with
excellent pasture, and elsewhere with heath or deep moss. The soil of
the gently rising district, though in some places thin and poor, is
mostly a fairly good earth, overlying gravel or stiff clay, and passing
in the haughs along streams into a good deep loam. Along the flat
district the soil is a rich alluvium, varying in depth from a few
inches to several feet, and in many places displaying all the
excellences of rich carse land. The processes of husbandry differ in no
respect from those employed in the neighbouring counties, and already
noticed. Westerly and south-westerly winds prevail on an average for
two-thirds of the year, and as they come directly from the Atlantic,
they are loaded with vapour, and the result of their contact with the
colder land is heavy rains. The western part of the county is, indeed,
one of the wettest parts of the W coast of the Scottish mainland, the
annual rainfall being about 60 inches. The mean temperature is about 48
degrees.
The areas under the various crops at different dates are given in the following tables:---
|
Year. |
Wheat. |
Barley or Bere. |
Oats. |
Total. |
1854 |
4495 |
613 |
16,392 |
21,400 |
1866 |
2973 |
234 |
14,229 |
17,436 |
1874 |
3346 |
259 |
13,645 |
17,250 |
1884 |
2229 |
178 |
14,132 |
16,639 |
1896 |
1320 |
167 |
12,259 |
13,746 |
|