Visit for New Members to Gullet Quarry

Tuesday 26^th April 2016

Field Trip led by Moira Jenkins

Although this was late April there was more than a chill in the air, with flurries of snow forecast on the hills.  We did not get snow but from time to time we were battered by hailstorms, while in between these storms the sun shone out in a clear blue sky so that we had an opportunity to see Gullet Quarry at its best.  In addition to the rocks nature also played its part with a peregrine falcon and some ravens attempting to divert our attention.

Before we set off from the car park Moira showed us some examples of the main rock types to be seen in the area-

· a pinkish granite and a darker rock, diorite.  These are the igneous rocks which form the main body of the Malvern Hills complex, dating from as much as around 600 million years ago (“mya”) in the Precambrian period; 

· a greyish brown series of rocks of sandstone and shale.  These are sedimentary rocks formed some 430-440 mya in the Silurian period and to be found immediately to the west of the Malvern complex rocks;

· a dark grey rock speckled with shiny chips of quartz.  This is a conglomerate formed around 500 mya in the Cambrian period and can be seen in just a few places at the boundary between the Precambrian and Silurian rocks.

On reaching the quarry we looked at the rocks in the stone wall on the eastern side of the quarry lake and saw many examples of granite and diorite together with a few blocks of an apple-green rock called epidote.  Moira explained that this is a metamorphic rock which would have formed deep below the surface where the igneous and sedimentary rock from which the epidote originated would have been subjected to tremendous forces of heat and pressure.

Walking along the pathway on the south side of the quarry lake we could see the walls of granite and diorite rocks towering up on the far side.  Underneath these, close to the level of the lake, we could also see grey rocks composed of Precambrian schist, another metamorphic rock formed deep underground.

We continued along the path for about 200 metres beyond the end of the quarry lake, going up the Gullet Pass to look at the remains of a small quarry where the Cambrian conglomerate rock could be seen.  Pausing there to shelter from a vicious hailstorm we saw how in places this rock was studded with small quartz pebbles. 

Re-tracing our steps we then climbed the steep path on the western side of the quarry until we reached an upper level where we could see the Precambrian rocks to our right while straight ahead and to our left were the many steeply-dipping layers of Silurian shales and sandstones.  Just between the two Moira showed where a layer of  rounded small rocks and pebbles are exposed, their shape being evidence that some 440 mya they rested here on a beach where the Silurian sea washed against the shoreline of a rocky coast composed of the igneous rocks formed in Precambrian times.

The Silurian shales and sandstones here are brittle and flaky, and the group found numerous examples of fossils in the form of casts of corals and brachiopods. 

So fascinated were we by what we saw in and around the quarry that our time ran out.  Several members were attending a fossils course in the afternoon, so today we did not have time to go onto the ridge of the Malvern Hills or see the volcanic rock around Clutters Cave.  We returned to the car park where Moira pointed out the line of the East Malvern fault, marking the boundary between the Precambrian rocks of the Malverns and those of Triassic age to the east where they underlay the Severn valley.  At the car park we were standing on the edge of Castlemorton Common, an area underlain with gravels deposited by glaciation in the last ice age.  Moira said the gravels rendered the Common useless for agriculture, which is why the Common is left for grazing. 

Despite the strange weather the morning’s trip was a great success.  There was disappointment at missing out on the views from the hills and not seeing the volcanic rocks, but this can be subject-matter for another trip.