THE MAKING OF CHESHIRE. I
THE NEWER ROCKS
There rolls the deep where grew the tree:
O earth, what changes hast thou seen!
There, where the long street roars, hath been
The stillness of the central sea.
Nearly every Cheshire boy has visited at some time or another a quarry
in the neighbourhood of the town or village where he dwells. He will
probably have noticed that beneath the two or three feet of soil at the
top of the quarry the rocks are arranged in beds or 'strata' piled one
upon another in horizontal rows, or sometimes sloping in parallel lines
towards the bottom of the quarry. When and how were these beds of rock
formed and laid down?
If our quarry is in the central or western parts of Cheshire we shall
find that the rocks are of a reddish colour, generally hard and gritty,
but sometimes so soft that pieces may be crushed into fragments with the
fingers. These rocks are known as the New Red sandstones, and are
largely used for building purposes. Chester Cathedral and a great number
of Cheshire churches have been built of this material; and the hillsides
where the rocks crop out above the soil often glow with a rich warm red
in the evening sunlight. You may see them best perhaps in the railway
cuttings in the neighbourhood of Frodsham and Chester, or in the great
quarries at Storeton-in-Wirral and Runcorn.
[Illustration: GEOLOGICAL MAP]
These beds of sandstone are really wide stretches of the sandy shores of
an ancient sea, which have been pressed into a solid substance by the
weight of other layers of rock deposited over them in later ages. Thus
they belong to a group of what are called 'water-laid' rocks. We know
that seas once flowed over them because some of the beds show the
ripple-marks that we see so often in the sands when walking by the
sea-shore. A fearful looking monster, with the equally terrible name of
labyrinthodont, in appearance rather like a gigantic frog, has left his
'footprints in the sands' in the rocks near Lymm and Weston. You will
probably not be able to find these footprints, but in the museums at
Manchester and Warrington you may see them on large slabs of sandstone
rock. How would you like to meet one of these reptiles to-day, wallowing
in the mud on the shores of some Cheshire mere? On the same slabs you
will see suncracks which tell us of the baking of sand and mud in the
sun's rays when the tide has gone down.
The lower layers of the New Red Sandstone are of a paler colour, light
brown or almost white. To these the name of 'Bunter' has been given to
distinguish them from the upper and therefore later deposits known as
'Keuper' sandstone. The Bunter beds are found chiefly in the west of the
county, and in Wirral, where you may see the Keuper rocks of Storeton
Hill sticking up above the layers of Bunter stone that surround and
underlie them.
The greater part of the surface of Cheshire consists of these rocks.
Alderley Edge and Helsby Hill, the hills of Delamere and Peckforton are
composed of it, and it crops out often in our village streets. The steps
of the village cross at Lymm are cut out of a piece of rock which sticks
out in the middle of the road.
In the sandstone beds at Northwich, Winsford, and Middlewich are layers
of rock salt from which we obtain our salt for food and other domestic
uses. The salt was formed at a time when the sea was gradually
disappearing from the surface of Cheshire leaving inland salt lakes,
which, becoming dried up, deposited beds of salt crystals. These, like
the sandstone, became pressed into a solid condition by the weight of
other layers. Where the salt has been taken out of the earth the upper
layers have sunk from time to time. At Northwich the land is continually
sinking, and you may see houses and chimneys cracked and twisted out of
their proper shape as if they had been visited by an earthquake. Often
the hollows where the land has sunk have become filled with water and
produced the numerous meres or small lakes dotted about the county. In
the valley of the Weaver they are locally known as 'flashes'.
[Illustration: STRIATED BOULDER (ERRATIC): HIGH LEGH]
When, in the course of time, the red sandstone formed the dry land of
Cheshire, it became covered by a great ice-sheet which extended over
Britain even as far south as the Thames valley. Beneath this covering of
ice the rocks were crushed and ground to atoms by the movement of the
ice-sheet over them. This formed beds of a substance called
boulder-clay, containing lumps of rock which must have been brought by
the ice great distances, for they are of a kind found only in the north
of England or in Scotland. Some of these 'boulders' are of great size.
Several have been placed in Vernon Park, Stockport, and in the West
Park, Macclesfield, you may see one that was dug up in the neighbourhood
of the town. It weighs about thirty tons. On Eddisbury Hill is a mass of
rock, ten feet long, of a kind found only on Skiddaw in the Lake
District, and in the narrow lane behind the 'Wizard' Inn on Alderley
Edge is a lump of granite from Eskdale, so that these rocks have been
brought by the ice a distance of a hundred miles. Such blocks and
boulders are called 'erratics', because they have wandered so far from
their original home. Another proof of the existence of the ice-sheet may
be seen in the scratchings and marks (called 'striae') on pebbles and
rocks found in these beds. In the lane outside the church at High Legh
are a number of large boulders which still show the lines of furrows and
scratchings made on their surface by the movement of the ice over them.
The boulder-clay has been worn away by the action of water and weather
from a great part of Cheshire, but in the west of the county large
patches may be seen in the low-lying districts. You may observe the beds
most clearly in the cliffs of boulder-clay on the estuary of the Dee
between Heswall and West Kirby. In the neighbourhood of Chester, many of
the villages--Tarvin, Christleton, Aldford, Saighton, and Barrow, for
instance--are built on sandstone knolls and ridges which stick up
through the boulder-clay, for the sandstone is drier and healthier than
the clay to live upon, and the wells, especially those in the Bunter
beds, provide the purest water.
As the ice-sheet melted and the glaciers or ice-rivers retreated
northwards when the climate became warmer, beds of sand, gravel, and
stones were spread over the Cheshire plain. These are called drift beds.
The stones and pebbles are rounded by the streams of melted ice and
snow which flowed from the mouths of the ice-rivers. Upon the beds of
drift lies the surface soil in which grow the crops and grass, the
herbage and the woods of to-day; and it is in the drift, as you will see
in a later chapter, that traces of the earliest inhabitants of Cheshire
are to be found.