Geography rocks and land use

Land use by humans

• Agriculture - around 85% of South Downs National Park is farmed, due to chalk grassland being ideal for grazing sheep, clay for grazing cows, and lower slopes for arable farming

• Forestry

• Many forests have been felled or replaced with faster-growing, non-native trees to improve the demanding timber industry

• Some regions have become more vegetated de to afforestation by humans

• UK charities such as Woodland Trust protect and increase forests

• Settlements

• Building materials recently haven’t reflected traditional design

• Downs suitable for spring line settlements built on south slopes, leading to 12,000 residents (most populated UK NP)

• Mostly rural area but some major towns and cities surrounding SDNP, like Brighton and Southampton

Metamorphic rocks

• Pre-existing rock whose shape or form has been changed by heat and/or pressure

• They contain regularly aligned crystals and can b shiny and hard, and sometimes flake into layers

• Contact metamorphism is when nearby igneous intrusions change characteristics in the rock

• Regional metamorphism occurs during an orogenic event (mountain building).When large continental plates collide, they create hue compressional forces that change the rock’s characteristics

Igneous rocks

• Rock that began as magma in the interior of the Earth.

• Formed when magma/lava cools and solidifies

• 2 types of igneous rock - extrusive and intrusive

• Extrusive formed when magma erupts and lava cools quickly on the ground. They typically have small crystals.

• Intrusive formed when magma is deep underground and intrudes into other rocks without reaching the surface, after which it cools slowly. They typically have larger crystals.

• Igneous rocks are impermeable.

Sedimentary rocks

• Rocks that began as sediment, usually on the seabed.

• When eroded fragments of rocks and organisms settled to form a sediment. Over millions of years, layers built up and are buried on top of one another and compressed by their own weight which squeezes out the water.

• They have a layered appearance called strata. May contain fossil remains of animals and plants that were trapped as the rock was formed and they can can be used to date the rock. They are usually permeable.

Batholiths and Tors

• A batholith is an enormous mass of intrusive igneous rock made of once molten material that has solidified below the Earth’s surface. They are only exposed after lots of erosion of overlying mountain. Dartmoor batholith is made of granite.

• A tor is a rock outcrop formed by weathering, and a result of magma at very high temperatures and deep underground being cooled very slowly a long time ago, causing crystal formation. It then solidified and got exposed when the soft rock above was eroded away.

• An example of a famous tor is Haytor in Dartmoor - it is ~300 million years old.

• Joints are create by shrinkage in the cooling granite and weakened by weathering widening them