ABC Wednesday - Q

This week the letter we have reached is Q

I start my Quest for Q at Ye Queens Head pub

Q is for Quarry, this quarry is near Stoke St Michael in the Mendip Hills

The rocks extracted from Moons Hill and Stoke Quarries are volcanic in origin and were formed some four hundred million years ago in the Silurian period of geological time. They form part of a renowned feature of British geological history and have been the subject of much debate and research over the years. The volcanoes which produced the lavas, ashes and other rock types extended over a wide area of what is now south west England. Rocks of the same type and age can be found in Devon and Gloucestershire.

Volcanic lavas, described as Andesites, were extruded over a wide area forming beds up to 100 to 150 metres thick. During the period of volcanic activity accumulations of volcanic ash also built up, sometimes overlying the lavas, sometimes interbedded with them. The fine-grained ashes are known as Tuffs and often contain blocks or cobbles of Andesite lavas; these formations are known as Agglomerates. Because of the presence of shales and mudstones below the volcanic rocks and sometimes interbedded with them, we know that volcanic activity was taking place in a marine environment. The whole sequence of lavas, ashes and agglomerates can be readily identified and measured in the Quarries because the beds are now standing vertically on end like books on a bookshelf. (www.wainwright.co.uk)

This is a disused quarry in the same area, the entrance to the quarry is now blocked by the huge blocks of limestone in the photo below.


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