4.1 - Geology in the UK Flashcards
Give a definition, approximate age, 3 examples and location in UK of igneous rocks.
Rocks that have formed by magma from molten crust rising to the surface and cooling to form solid rock. These vary in age, from billions of years to mere minutes. Examples include Andesite, Basalt and Obsidian.
Give a definition, approximate age, 3 examples and location in UK of sedimentary rocks.
Rocks transported, and broken up, by rivers, streams, and oceans. They are around 700 million years old, and examples include Limestone, Sandstone, and Slate.
Compare metamorphic and igneous rocks.
Metamorphic rocks are formed under extreme pressure or heat, whereas Igneous rocks are formed when hot magma cools down.
Compare the formation and characteristics of Granite and
Granite is Igneous, so it is formed from the slow crystallisation of magma below earth’s surface. Carboniferous Limestone is sedimentary, so it is formed from the remains of organic matter.
Compare the formation and characteristics of Chalk and Slate.
Chalk is a sedimentary rock made of Calcium Carbonate. It is permeable.
Slate is a metamorphic rock, created by Shale or Mudstone, under extreme amounts of pressure.
Explain when and how active volcanoes shaped the uplands of the UK
450 million years ago, the UK was on a destructive boundary. Because of this, massive fold mountains and Volcanoes were formed, from the subduction and movement of magma through convectional currents.
Explain how glacial erosion and deposition shaped the UK uplands
The base of glacier ice melts because of pressure and friction. This allows water to freeze into cracks in the rocks and when the glacier moves it pulls out chunks to leave a jagged surface.
This provides material for abrasion and this process is called plucking. Rocks which get stuck in the ice grind away the bedrock under the glacier and this is known as abrasion.
Freeze thaw, or frost shattering, is a process of weathering that also occurs in upland areas. Water in cracks in the rock freezes and expands, forcing open the gap. When the ice melts more water can get into the crack and freeze again.
After many cycles of freezing and thawing lumps of rock are broken off the surface - this is called freeze thaw. These small pieces of rock are called scree and often build up forming scree slopes on mountainsides.
Explain when and how sedimentary rock was formed across the UK Lowlands.
Millions of years ago, the UK was underneath a tropical sea. This allowed the perfect conditions for sedimentary rock to form. Sedimentary rocks are formed from sediments that have settled at the bottom of a lake, sea or ocean, and have been compressed over millions of years. The sediment comes from eroded rocks carried there by rivers or ice, and from the skeletons of sea creatures.
Explain how glacial deposition shaped the UK Lowlands
Glaciers picked up igneous rocks from the UK’s uplands during the ice age, where they then transported the rocks into lower, flatter land before melting. This lead to large rocky outcrops in the lowlands.
Explain how scarp and vale topography forms in the UK Lowlands
Formed by erosion or faulting and separates two relatively level areas of differing elevations. The destructive boundary that used to be on the UK folded the landscape and creating a huge anticline. This anticline’s dome then eroded, eroding away the chalk at the top of the dome. The chalk at the sides of the dome, however, still remained, forming steep escarpments (scarp slopes).
