Cheshire

by Charles E. Kelsey

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'.

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.