Mark Wilson June 25th, 2015
BRISTOL, ENGLAND (June 25, 2015) — Our little geological exploration of southern Britain now passes into England. Tim Palmer and I crossed the River Severn and drove to the Cotswolds to examine old quarry exposures and Medieval stonework. We are parked above in Salterley Quarry near Leckhampton Hill.
Our theme again is Jurassic. At Leckhampton Hill we examined exposures of the Middle Jurassic Inferior Oolite. It is not, of course, inferior to anything in the modern sense. The name, originally from William Smith himself, refers to its position below the Great Oolite. This is Devil’s Chimney, a remnant of stone left from quarrying in the 19th Century.
We stopped along a bend in a Cotswold road called Fiddler’s Elbow and found an old carbonate hardground friend in the Inferior Oolite. Borings are evident in this flat, eroded surface. Next to the hammer are pieces of the Pea Grit, a coarser facies. I want to examine the grains for microborings and encrusters.
A closer view of the orchids. When I learn the name for this plant, I’ll amend this post. [And we have one! Caroline Palmer identified the flowers as Dactylorhiza sp. Thanks, Caroline!]
At the end of the day we stopped by St. Mary’s Church in Painswick, with its distinctive churchyard and variety of building stones. The sculptured trees are English yews.
Many of the gravestones have copper plates affixed to their upper faces. The rain washes copper ions out of the metal and over the limestone, killing the lichens and other encrusting organisms. This leaves the lighter patch of bare limestone. Somewhere in this is a study of microbiome ecological gradients!
The Painswick church was the site of a 1643 battle during the English Civil War. There are numerous bullet and shot marks on the exterior stones. Tim commented on the remarkable resilience of this stone to stay coherent after almost 400 years of weathering of these pits.