Shallow, oxygen deficient seas still covered the Malvern area during the Lower Ordovician, resulting in the deposition of the Bronsil Shales. During this time the southern continent of Gondwana was slowly moving northwards. This started the closure of the Iapetus Ocean and resulted in renewed volcanic activity in the Lake District and Wales. Igneous activity also resumed within the Malvern area and a series of intrusive igneous rocks which were injected into the Cambrian and lower Ordovician sediments in response to the subsidence of the Welsh Basin.
The igneous intrusions are in the form of dykes and sills, which form ridges trending in a north-westerly direction. The Ordovician igneous intrusions are present in the southern end of the Hills, between Whiteleaved Oak and Ragged Stone Hill. They have left their imprint upon the landscape as the presence of these resistant igneous rocks within the weaker Whiteleaved Oak and Bronsil Shales has produced an undulating topography. For example, a large sill forms a broad ridge extending north-west from Chase End Hill (SO761355) and Whiteleaved Oak (SO762359). The irregular-shaped intrusions or bosses have formed a prominent knoll 200 metres north of Bronsil Castle (SO762359) (Figure Five).
Towards the end of the Ordovician Period there was a global drop in sea level caused by a major ice age centred on Gondwana. Evidence of this Ordovician glaciation has been preserved in the Sahara, South America and Arabia. The Malvern area was above sea level once again, forming part of a landmass bounded to the west by the Welsh sea. By the end of the Ordovician, the area had moved northwards and was located approximately 40 Degrees South of the Equator (Figure Six).
