Geology

The following article discusses the geology of the malvern ridge and surrounding landscape. To see a west-east cross section diagram to accompany the explanation click the link below.

Geological Cross Section of the Malvern Hills

A division between Herefordshire and Worcestershire is created by the ancient granite rocks of the Malvern Hills, separating the rolling hillsides to the west from the flat Severn plain on the east. This creates three unique landscapes each with different geological origins.

The Malvern ridge - Malvernian Granite

The granite of the Malvern Hills was formed more than 600 million years ago during the Precambrian period, prior to the appearance of animals with hard parts and thus, no fossils exist. It seems that around 400-500 million years ago, during the Silurian period, the area was covered by a warm sea sheltering coral reefs and the vast myriad of life and organisms that such an environment sustains. Towards the end of this period this part of the world became unstable and tremendous pressures in the Earth’s crust forced the Precambrian granite upwards, taking the sea bed with it, and formed the ridge of the Malverns. The softer sediments of the sea bed were eroded away over time leaving the harder Malvernian granite ridge as we know it today. It was another phase of earth movement during this period that thrust the Herefordshire Beacon (British Camp) westwards.

There are a number of fault lines across the Malvern hills and these mainly run east to west creating several passes between the peaks, for example at the Gullet Quarry to the north of Midsummer Camp. To the east the hills are bounded by a fault line which runs from north to south.

To the west – Herefordshire - Limestone & shales

The Herefordshire landscape to the west of the hills consists of sedimentary rocks that are much younger than the granite of the hills themselves. They are formed by the sediment of the creatures coral and mud that were present when the area was covered by water. During periods when the sea was shallow mud was the main deposit and this results in shale. Deeper, clearer areas of the sea allowed for shelly deposits and coral reefs which later have formed limestone. Over hundreds and thousands of years limestone and shale have alternated and become tilted and twisted during the rise of the granite ridge and the formation of the Herefordshire Beacon. If one is to survey the scenery to the west of the hills at this time, the softer shales are mainly farmland while the harder limestone ridges and hilltops remain for the most part wooded.

To the east – Worcestershire – The Severn plain

During the periods following the Silurian it is probable that other layers were formed which have since been eroded away, with the exception of the eastern side of the ridge. Some 200 million years ago during the Triassic period Mercia mudstone (formerly Keuper Marl or Trias Marl) was deposited in inland lakes. Also during this period there was a continuing accumulation of red desert sandstones deposited by rivers and dunes. This has left flat beds of soft red sandstone across the plain.