The Formation Of Granite Tors

The softer rock above the batholith erodes away over time leaving the batholith exposed to the elements.

The formation of granite tors.

During daytime rocks are expose to the baking sun they expand due to the increase in temperature. The granite seen on dartmoor originated as a granite batholith under the surface of the earth. The formation of tors on dartmoor. A batholith is an area of molten rock that has cooled very slowly within the crust creating a rock with large crystals.

Tors are landforms created by the erosion and weathering of rock. The formation of a granite tor. The formation of granite tors for gcse geography 9 1. Tors are seldom more than 15 metres 50 feet high and often occur as residues at the summits of inselbergs and at the highest points of pediments.

Tors usually overlie unaltered bedrock and are thought to be formed either by freeze thaw weathering or by groundwater weathering before exposure. Alternate contraction and expansion of the rock cause the joints or cracks present in the rock to be widen. Many hypotheses have been proposed to explain their origin and this remains a topic of discussion among geologists and geomorphologists and physical geographers. Over time the material above the batholith was weathered and removed by rivers and glaciers.

At night due to radiate cooling effect the rocks are cooled rapidly and they contract. Generally the slower the molten rock cooled the larger it s mineral crystals with k feldspar megacrysts forming in special circumstances greater than 5cm. While the rock is cooling it starts to contract causing cracks these also occur when the batholith is exposed and pressure is released. There is often evidence of spheroidal weathering of the squared joint blocks.

The processes resulting in the formation of the dartmoor tors started about 280 million years ago as the granite forming dartmoor cooled and solidified from molten rock at a. Granite tors start to form when magma that has intruded into the crust cools to form a batholith. Most commonly granites but also schists dacites dolerites ignimbrites coarse sandstones and others.