Troopers Hill - A 300 million year story
Troopers Hill’s geology is unusual in Bristol. Much of the city lies on Carboniferous Limestone, but Troopers Hill is dominated by sandstone of the Pennant Measures. These sedimentary rocks were formed 300 million years ago when this area was on the equator, when it was a place of rivers and swamps, covered by a forest of primitive plants. The sediments formed at the time hardened into rocks and they were tilted steeply to the south by massive earth movements. In places, the sandstone can be seen on the surface, both as natural outcrops and old quarry faces.
Much of the shape of the hill is the result of quarrying for the sandstone which was used as building stone throughout Bristol. As well as sandstones the Pennant Measures include mudstones, shales, clay and coal seams. The chimney is thought to have been used for copper smelting in the late 1700s. Later, in the 1800s, coal and fireclay was taken from deep mines under the hill perhaps accounting for the lean of the chimney. The largest quarry was the gully in the centre of the hill which was worked until the end of the nineteenth century. The humps and bumps on the hills are where the unsuitable stone was tipped.
The combination of sandstone and local industry has resulted in acid soils, which are rare in Bristol. This has encouraged a wealth of plants to flourish, that are found nowhere else in the city.
Questions
To log this cache you must visit the posted coordinates on Troopers Hill and answer the following questions. Please send the answers via email or message. There is no need to wait before logging the cache. Please provide the answers within a reasonable timescale. Logs will only be deleted if you have not visited or if your answers are drastically incorrect.
1) Observe and touch the surface of the chimney. Describe its colour and how it feels. What stone do you think the chimney is made of? Why is the chimney made of this rock?
2) In the 'Fireclay' section on the noticeboard how many seams of fireclay are under the hill?
3) Take a photo of you/your GPS on Troopers Hill and post it with your log or with your answers.
I hope you enjoy your visit to Troopers Hill, it is a very special place with incredible views. Please note I have included a reference waypoint in the gully below. Here you can spot fossil plants embedded in the rocks. Please mind your step if you do descend into the gully as the terrain is steep and rocky in places.