Cheshire has some remarkable geology.  For example, over the weekend we visited the Dee Cliffs at Farndon.  This is a Site of Special Scientific Interest (SSSI). These sandstone strata were laid down during the Triassic Period.  At this time in Earth’s history, much of England was low-lying desert, with an extremely hot and arid climate. Wind-blown sand formed huge dunes reminiscent of today’s Sahara Desert. The dry desert landscape was punctuated by ephemeral lakes and seasonal rivers, carrying sediment from large mountain ranges in the north, west and south. The rivers deposited their sandy sediment, which over millions of years hardened to form sandstone.

The red colour of the rock is caused by oxidation of iron (rust) in the desert conditions.

Triassic sandstone cliffs exposed alongside the River Dee in Cheshire.

In this photograph of a sandstone outcrop, the sloping angles of the beds can be clearly seen. This is referred to as “cross-bedding” and it is usually formed when sediment is deposited in fast-flowing rivers. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Cheshire’s Triassic Sandstone Cliffs

Layers of sandstone can be identified in these cliffs. They slope at various angles. This is referred to as “cross-bedding” and it is formed when sediment is deposited in fast-flowing rivers or strong ancient winds.  The cross-bedding provides a record of ancient palaeocurrents (wind or water).  These sedimentary structures are inclined at an angle to the main bedding plane. Cross-bedding is a primary sedimentary structure, meaning it forms when the deposits are laid down. It’s a valuable tool for geologists as it helps interpret depositional environments. For example, geologists can determine the direction of the water flow by examining these structures.

Triassic sandstone cliffs show cross-bedding (Dee Cliffs in Cheshire).

A close-up view of the Triassic sandstone cliffs that line the eastern side of the River Dee which marks the border between England and Wales. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Seeing these ancient structures helps us to appreciate that remarkable geology that can be seen around Cheshire.  These sandstones provide a window into deep time and highlight an extreme palaeoenvironment.

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