The Formation Of Granite Tors

Over time the material above the batholith was weathered and removed by rivers and glaciers.

The formation of granite tors.

The formation of granite tors for gcse geography 9 1. At night due to radiate cooling effect the rocks are cooled rapidly and they contract. The formation of tors on dartmoor. Granite tors start to form when magma that has intruded into the crust cools to form a batholith.

A batholith is an area of molten rock that has cooled very slowly within the crust creating a rock with large crystals. 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. Many hypotheses have been proposed to explain their origin and this remains a topic of discussion among geologists and geomorphologists and physical geographers. Generally the slower the molten rock cooled the larger it s mineral crystals with k feldspar megacrysts forming in special circumstances greater than 5cm.

The granite seen on dartmoor originated as a granite batholith under the surface of the earth. Tors are landforms created by the erosion and weathering of rock. Alternate contraction and expansion of the rock cause the joints or cracks present in the rock to be widen. The softer rock above the batholith erodes away over time leaving the batholith exposed to the elements.

One clear consequence of frost action on the granite has been the formation of rock basins locality1a not only on the upper surfaces of the tor core stones but also on occasions on larger clitter blocks clearly indicating that basin formation must have occurred recently. Granite is an intrusive igneous rock which means it was formed in place during the cooling of molten rock. While the rock is cooling it starts to contract causing cracks these also occur when the batholith is exposed and pressure is released. Tors are mostly less than 5 meters 16 ft high.

Most commonly granites but also schists dacites dolerites ignimbrites coarse sandstones and others. Tors usually overlie unaltered bedrock and are thought to be formed either by freeze thaw weathering or by groundwater weathering before exposure. The formation of a granite tor.