Rock Outcrops

There are two large blocks of rock that have been left standing and not removed by the quarrying operations in Edgar's Field. Their overall red colour is caused by iron oxide. Many of Chester's buildings are built of, or incorporate, such red sandstone. 

 

 

The exposed vertical face of the outcrop nearest to the river, in particular, shows a number of geological structures including:

 

Cross Bedding

These are sequences of thin layers of rock at obvious angles with the set of layers above at different angles to the set below. This structure reflects the manner of the deposition of the sediment in sand bars in the prehistoric braided (multiple channel) river. When the river channels moved, the bars changed position to give these different angles.

Slumping

Here the rock is wavy and distorted. This structure is caused by the collapse of soft wet sediments so that different layers become buckled.

Differential Weathering

Weathering is the natural process (for example, due to water and frost) by which rock is broken into fragments. This process returns sandstone into sand. Differential weathering occurs when different layers of rock are worn away at different rates because some layers are softer and more easily weathered than others.