This information was published on our original website in 2014. We are in the process of updating the information, as some of the contents may be out of date.
Introduction
The Malvern Hills are comprised of rock formations of outstanding geological interest, which span over 700 million years to include some of the oldest rocks in England (Figure One). These rocks tell a fascinating story of continental collisions, shallow tropical seas, hot deserts, tropical swamps, vast ice sheets and polar deserts. These changes in ancient depositional environments, combined with past and current physical processes have produced the diversity of landscapes and scenery that can be seen today.
The Geological History of the Malvern Hills
This table shows what deposits from each period of geological history are present in the Malvern Hills and where.
| Age (millions of years) | Eon | Era | Period | Depositional Environment |
|---|---|---|---|---|
| present day to 1.8 | P H A N E R O Z O I C | C E N O Z O I C | Quaternary | Cold climatic conditions with intervening temperate conditions. Early glacial activity resulted in the formation of ice dammed lakes to the west of the Malvern Hills. Intense Periglacial conditions resulted in freeze-thaw and slope failure. |
| 1.8 to 2.4 | Neogene | Not represented in the Malvern Hills. | ||
| 24 to 65 | Palaeogene | |||
| 65 to 142 | M E S O Z O I C | Cretaceous | Not represented in the Malvern Hills. Removed by erosion following earth movements associated with the collision between the African and European continents to form the Alps (approx. 65 million years ago). | |
| 142 to 205 | Jurassic | Not represented in the Malvern Hills. Removed by erosion following earth movements associated with the collision between the African and European continent to form the Alps. | ||
| 205 to 248 | Triassic | Arid desert, crossed by large braided streams. Shallow playa (salt) lakes covered large parts of the Worcester Basin. | ||
| 248 to 290 | P A L A E O Z O I C | Permian | Arid rocky desert, alluvial fan deposits and wind blown deposits (sand dunes). | |
| 290 to 354 | Carboniferous | Not represented in the Malvern Hills due to period of uplift associated with the formation of the large super- continent of Pangaea at the end of the Carboniferous. | ||
| 354 to 417 | Devonian | Semi-arid conditions. The land surface was exposed for a prolonged period of time allowing soil formation. | ||
| 417 to 443 | Silurian | Rising sea levels. The Malvern Hills were located at the edge of a warm shallow sea associated with coral reefs. Towards the end of the Silurian the conditions changed to continental deposition and streams migrated over a semi-arid alluvial plain. | ||
| 443 to 495 | Ordovician | Shallow oxygen deficient seas. A large proportion of the Ordovician has been removed in response to a period of uplift. Renewed igneous activity resulted in the intrusion of a series of dykes and sills towards the southern end of the Malvern Hills. | ||
| 495 to 545 | Cambrian | Shallow seas gradually covered the erodedPrecambrian Land surface. | ||
| 545 to 1000 | Proterozoic | Precambrian | Ocean floor volcanic eruptions. Plutonic igneous activity associated with island arc formation. These plutonic igneous rocks form the main ridge of the Malvern Hills. |
|
| 1000 to 2500 | Archean | |||
| 2500 to 4600 | Hadean |
Contrasting landscapes
The main body of the Hills is comprised of a North to South trending ridge of Precambrian igneous and metamorphic rocks which separates the counties of Herefordshire and Worcestershire. The extremely resistant nature of these rocks has contributed towards the elevated nature of the Hills in comparison to the surrounding landscape, which is underlain by much weaker rocks. On the western side of the Hills a succession of folded bands of Silurian limestones and shales has produced the classic ridge and vale topography of this part of Herefordshire.
On the Eastern side of the Hills, a thick sequence of Permian and Triassic sandstones and mudstones has produced the relatively flat topography of Worcestershire and the Severn Valley. Although the elevated nature of the Hills is closely related to the resistant nature of the underlying geology, it is also important to appreciate that the overall shape of the hills have been influenced by tectonic processes. Throughout their geological history, the Hills have experienced length periods of uplift, folding and faulting in response to several continental collisions and separations. For example, compressive forces caused by the collision of Europe and Africa during the late Carboniferous period have resulted in large scale folding and the development of a series of faults which cut across the Malvern ridge. The faults have disrupted the North to South alignment of the Hills, displacing Herefordshire Beacon and Chase End Hill westwards so they are no longer aligned with the rest of the Hills.
Late Carboniferous thrust faulting
Compressional Forces operating during the late Carboniferous Period have formed a series of thrust faults, displacing the Malvern ridge to the west. The Warren House Formation has been thrust against the Malverns Complex.
The Precambrian rocks at Herefordshire Beacon have been displaced westwards and now lie on top of younger Silurian rocks.
