Summary of the Local Geology
Running north-south through the middle of Cheshire is a sandstone ridge of hills called, the Mid-Cheshire Ridge. There is a north-south geological fault immediately to the east of the ridge (the Peckforton Fault). To the west, the exposed rock is sandstone. The land to the east has dropped and the salty rock has been protected from erosion, so that the area around Northwich and Middlewich has been an important salt supplier since Roman times.
Interesting Fact: You can visit the Lion Salt Works in Northwich, Cheshire which is now a museum about the History of salt in Cheshire (around Northwich and Winsford), Due to Health & Safety you are no longer allowed in the Salt Mines in Winsford.
You can find more information about the History of Salt in Cheshire by visiting the Lion Salt Work Museum’s Website here
You can also read more about the Winsford Salt Mine (The UK’s largest salt mine) here on the BBC Website
Alderley Edge (A Site of Special and Scientific Interest)
Alderley Edge Geology is very important for the Geology of Cheshire, due to its Geological Value to area has been designated by the Government as a SSSI (Site of Special Scientific Interest).
Alderley Edge is made of sandstones which dip from the Edge at about 12 degrees. The sandstone is not one solid mass but is in layers many metres thick. Each layer or ‘bed’ is slightly different in origin, hardness and colour. All the rocks at Alderley were laid down about 250 million years ago in the Triassic era.
The Youngest rocks at Alderley Edge are the West Mine Beds which are formed from air-borne sand and are the widest layers at the Edge. Below these beds are the Wood Mine beds formed of alternating layers of conglomerate, water-deposited sandstone and clay. Below these again are the hard beds of the Engine Vein sandstones which form the bottom of the Helsby Sandstone Formation. It is these beds which show at Stormy Point and provide the weather-resistant rocks that form the Castle Rock. Finally, appearing at the bottom of Stormy Point, are the soft rocks of the Wilmslow Sandstone formation. These rocks are all in the Sherwood Sandstone Group.
I will be covering the Mineralogy and Local Minerals in Cheshire on our Cheshire Mineralogy Page
Local Geology (Helsby & Manley)
Geology Of Manley, Cheshire – Manley Quarry was one of the few quarries in Cheshire which produced a white as opposed to red sandstone. In reality the newly hewn stone, which could be extracted in very large blocks, was a buff cream colour which weathered to grey. The stone takes a fine ashlar finish and is readily carved and finished especially when new. Its weathering qualities are excellent for it does not flake or decay like the red sandstone. Although it has been used for local buildings it has also been used for many major ones such as Thomas Harrison’s great neoclassical castle at Chester, Chester Town Hall, Eaton Hall, St Michael’s Church and the Trustee Savings Bank in Chester. The great exploitation of the quarry began around 1790 and from that time to 1820 the County Justices spent a good deal of money on the improvement of roads around Manley to facilitate the transport of the stone. It was also used in the construction of railway bridges and in the Manchester Ship Canal.
Local men worked in the quarry, there was an accident in the quarry with injury and death to some men and it was subsequently closed down. It was reopened by Mr. Armitage for extraction of stone with which he could extend his house in the 1920’s and then left so that it developed into a natural nature reserve. Unfortunately it was subsequently used as a rubbish tip.
Geology of Helsby, Cheshire – The Helsby Sandstone Formation (named from the Cheshire village of Helsby where the type section is exposed at Helsby Hill) comprises around 250m thickness of sandstone with conglomerate and siltstone which occurs across the Cheshire Basin. Older literature includes it as part of the Lower Keuper Sandstone. It is often divided into an upper Frodsham Member and a lower Delamere Member. Faulted blocks of these rocks are largely responsible for the prominent west facing escarpment of the Mid Cheshire Ridge and the Helsby Sandstone is exposed in numerous localities here, southwards from Runcorn through Frodsham to Utkinton, spectacularly at the outer of Beeston Castle hill and lastly within the Peckforton Hills.