Rocks And

Lansdscapes

Types of Rocks -Igneous rocks: From volcanic activity.-Sedimentary rocks: Either of small particles of other rocks that have been eroded and transported or of the remains of plants and animals.-Metamorphic rocks: Altered by extremes of heat and/or pressure.

Weathering

-Weathering includes the

breaking up and decay of rocks in

places where they formed.Types of

Weathering -Physical, chemical

and biological

Physical Weathering

*Freeze-thaw-Scree: Where the broken-off rocks collects at the foot of a cliff.

-Exfoliation: It occurs in very warm climates where exposed rock is repeatedly heated and cooled, this causes the outer layers to peel off.

Chemical Weathering -It is when water and air

activate chemical changes that cause rock to rot and

decay. Chemical reactions are greatest where the climate is

very warm and wet.

Limestone

Solution-It is an example of chemical weathering, when carbonic acid, which occurs naturally as a weak solution in rainwater, reacts with rocks such as limestone that contain calcium carbonate. As the limestone slowly dissolves, it is removed by running water to create distinctive landforms.

Biological

Weathering -It occurs when either tree roots penetrate and widen cracks in a rock (physical) or acids, released by decaying vegetation, attack the rock (chemical).

The Structure of a Rock can affect

-Its resistance to erosion and its permeability to

water.

The Rock

Resistance-The harder the rock, the

more resistant it is likely to be to erosion. Hills and

mountains tend to form in areas of harder rock while valleys are found on softer

rock.Permeability

-Impermeable rock has numerous surface rivers and

may be badly drained, in contrast to permeable rock

which has few surface rivers; groundwater instead.

What do chalk areas look like?

-Chalk, which is a soft limestone, occurs in

south-east England. It is permeable and so, as it is relatively resistant to

erosion, it can form:

*Low-lying, gently rounded hills

*Ridges (escarpments)

Limestone -It is a rock consisting mainly

of calcium carbonate, which

comes from the remains of

sea shells and coral. Types of

limestone are Carboniferous

limestone, Jurassic limestone

and Chalk.Type of limestone

forms:-Each type produces its own special type of scenery, with karst landforms developing in areas of Carboniferous

limestone.

Why Carboniferous limestone produces distinctive

landforms? -Chemical weathering-Rock structure -Permeability

When a river reaches limestone?

-It begins to dissolve joints and bedding planes.

Underground Caves.

-Sometimes solution is so active that form underground caves.

Stalactive-As the water drips, some of it will slowly evaporate and calcium carbonate is deposited: in time a stalactite will form: it is an icicle shaped feature which hangs downwards from the roof.

Stalagmite-As the water drips to the floor, further deposition of calcium carbonate forms stalagmites, features that grow up from the cave floor.

Resurgence-The river flow over the

impermeable rock until it reaches the surface. The place where it reappears

is called resurgence.

People have

quarried rocks? -People have quarried rocks and minerals from the earliest times –initially flint for axes and tools and later stone and slate for building materials.

Quarrying-It is when rocks are

taken straight from the

Earth’s surface –unlike

mining where workers

have to operate

underground.

The End