an introduction to geology - u3asites.org.uk · coal measures/shale gritstone limestone. geology -...

An Introduction to GEOLOGY

…is an earth science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which they change.

Geology

Geomorphology

Petrology

Mineralogy

Crystallography

Vulcanology

TectonicsSedimentology

Seismology

PalaeontologyMicro-

palaeontology

Geophysics

GEOLOGY

Geography

Chemistry Physics

Biology

Glaciology

Stratigraphy

CORE

MANTLE

CRUST

SUBDUCTION

UPWELLINGCONVECTION IN MANTLE

The Geological Succession

CARBONIFEROUS

Gritstone

Coal Measures/Shale

Limestone

Sandstone

Typical English Carboniferous Series

(Silurian, Devonian)

((Permian, Triassic)

Gritstone

Coal Measures/Shale

Limestone

Sandstone

Typical English Carboniferous Series

Tectonic Forces

Typical English Carboniferous Series

Tectonic Forces

Sandstone

Coal Measures/Shale

Gritstone

Limestone

Geology - Summary• The earth is 4.4 billion years old• This lifetime is divided into the Eons, Eras, Periods & Epochs of the Geological Succession• The earth consists of a solid core, a liquid mantle and a solid crust• Convection in the mantle generates tectonic movement of the crust’s plates• In turn, Tectonic movement generates folding, faulting, volcanic activity and earthquakes• All rocks in the crust originate from within the earth’s mantle, as Igneous

• Wind, water & ice erode the rocks to create sediment which forms Sedimentary rocks

• These are changed by heat & pressure when in contact with further volcanic activity, forming Metamorphic rocks

• Sedimentary rocks are laid down in layers; Metamorphic rocks may also retain their original layered structure • Igneous rocks may be crystalline, columnar or smooth & glassy • Sedimentary rocks may be grainy to fairly smooth• Sedimentary rocks are usually permeable but not always porous• The Geological Succession shows us primarily when the sedimentary rocks were laid down;

but igneous & metamorphic activity can happen at any time• So can tectonic movement, folding, faulting volcanoes & earthquakes• The geology of the British Isles is complex and includes some of the world’s oldest rocks • The National Parks of the Pennines & Cumbria illustrate much of this variety and impact on the landscape • Ice as well as water has sculpted many of the landscape features we see today

Geology:– How to spot its impact on the landscape

• Look for exposed rocks in cliffs, cuttings & quarries• Is it layered, faulted &/or folded?• Is it crystalline, granular or smooth? • Can you see any fossils in it?• Does it look the same as other rocks nearby?• If not, can you see the join? • Does the vegetation reflect the type of rock?• Does the vegetation follow the lie of the land?• Are the valleys V-shaped by rivers, or U-shaped by glaciers?• Is there any natural surface water (rivers or lakes)?• Are there any natural caves?• Etc etc

…These are all clues as to what rocks there are and by what processes they affected the landscape