User:Bsrboy/Sandbox

The geology of Plymouth has a mixture of Limestone, Devonians slate, Granite and Middle Devonian Limestone. The bulk of the city is built upon Upper Devonian slates and shales, which have been greatly folded and faulted and the rocks become progressively younger from South to North. The headlands at the entrance to Plymouth Sound are formed of Lower Devonian slates, which can withstand the power of the sea. A band of Middle Devonian limestone, formed from the coral reefs that grew in warm shallow waters, runs west to east from Cremyll to Plymstock including the Hoe. Local limestone may be seen in numerous buildings, walls and pavements throughout Plymouth. There is evidence within the city of the volcanic activity of the Devonian period at such places as Ford, Hartley and Plymstock. To the north and north east of the city the granite mass of Dartmoor has had a profound impact on climate and economic activity. Granite has historically been exported around the world via Plymouth. Rocks around the edge of the Dartmoor granite mass were not only changed by the heat of the intrusion but were also heavily mineralised by fluids driven by the heat. This has given rise to ores containing tin, copper, tungsten, lead and other minerals in the Tamar Valley.^[1] The middle Devonian limestone belt in the south edge of Plymouth and in Plymstock has been quarried for many years. There is clear evidence of former activity at West Hoe, Cattedown and Radford. Currently quarrying takes place at two sites in Plymstock where the limestone has been worked over the last hundred years.^[2]