Rocky Landscapes Key Words

A naturally occurring solid mass or aggregate of minerals or mineraloid matter.
The creation of something or a structure or arrangement of rock.
Liquid or semi-liquid molten rock beneath the Earths surface.
Liquid or semi-liquid molten rock above the Earths surface.
Igneous rock is formed through the cooling and solidification of magma or lava.
Igneous rock formed inside the Earth.
Igneous rock formed outside the Earths surface.
Rocks that are formed by the accumulation of deposited minerals, sediment or organic particles. They are normally formed under great amounts of pressure.
A type of rock formed by the changing of state of existing rock through extreme heat and pressure normally cause through tectonic processes.
The process of sediment settling, being deposited or coming to a stop in a single location.
The squeezing together of sediment by pressure, this reduces the space between sediment and eventually forms sedimentary rock.
The joining together of sediments to form new rock.
To bind particles together. It is also a powder like substance used in the creation of concrete.
A huge slab of solid rock that rests on top of the Earths mantle. These are normally 1000’s of KM in diameter.
Rocks made by or modified by humans.
A heavy, rough building material made from a mixture of broken stone or gravel, sand, cement, and water, that can be spread or poured into molds and that forms a mass resembling stone on hardening.
A man made rock that imitates the properties of naturally occurring rock.
A small rectangular block typically made of fired or sun-dried clay, used in building
The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous.
A rupture in the crust of the Earth that allows magma to rise to the surface, these can take many shapes and forms.
The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
Allows liquids to pass through it.
Does not allow liquid to pass through it.
Able to withstand wear, pressure, or damage; hard-wearing.
A measure of how compact a substance is.
The process of wearing or being worn by long exposure to the atmosphere.
The gradual destruction or diminution of materials.
The dropping or laying down of sediment.
Weathering that occurs due to atmospheric changes.
Changes made to the molecular structure of rocks normally due to the acidity of water.
The weakening and subsequent disintegration of rock by plants, animals and microbes.
Type of landscape where the dissolving of the bedrock has created sinkholes, sinking streams, caves, springs, and other characteristic features.
An icicle-shaped formation that hangs from the ceiling of a cave and is produced by precipitation of minerals from water dripping through the cave ceiling.
an upward-growing mound of mineral deposits that have precipitated from water dripping onto the floor of a cave.
An industry that drives people to travel for recreation and leisure. The growth of tourism has had an economic, environmental and social effect on many countries.

Start of Content

The Basic Questions

What are rocks?

A rock is a naturally occurring solid mass or aggregate of minerals or mineraloid matter. Rocks are the ground beneath our feet and are the basis of the walls around us.

Why can you find rocks everywhere?

4.5 billion years ago, high-speed collisions between dust and space rocks formed the beginnings of our planet: a bubbling, molten sphere of magma that was thousands of miles deep. As this magma cools it turns back into rock. The Earth is made of rock, that’s why it is everywhere!

Are rocks alive? How do we know?

Rocks are non-living. We know this because they do not respire, eat, drink, think or feel.

How do rocks form?

Rocks form in several different ways. The most common of which are:

From cooling and solidifying lava and magma
From an accumulation of sediment and pressure.
By rocks changing state through heat and pressure

The Types Of Rock

A - Extrusive Igneous Rock

Formed when lava is ejected from volcanos or other breaks in the Earths crust and it then cools quickly and forms rock normally with a small crystal structure.

Examples include:
- Andesite
- Basalt
- Dacite
- Obsidian
- Pumice
- Rhyolite
- Scoria
- Tuff.

B - Intrusive Igneous Rock

Formed when Magma cools slowly still within the earths crust and forms rock, normally with a large crystal structure.

Examples include:
- Diabase
- Diorite
- Gabbro
- Granite
- Pegmatite
- Peridotite

C - Sedimentary Rock

Formed when sediment (small pieces of rock) build up over time into layers. Normally on the bottom of a deep body of water. These layers then create pressure to force the sediment to combine into one solid mass. Some of the key characteristics of sedimentary rocks are layers.

Examples include:
- Sandstone
- Limestone
- Shale

D - Metamorphic Rock

Formed when rocks are subjected to high heat and large amounts of pressure. Conditions like these are found deep within the Earth, where tectonic plates meet or around volcanic regions.

Examples include:
- Slate
- Marble
- Soapstone
- Quartzite
- Amphibolite

The Rock Cycle

The rocks on our planet do not remain the same way forever. They are constantly changing state due to processes such as erosion, weathering, pressure, melting and cooling. The rocks gradually change over thousands, if not millions of years.

An example of a journey that a rock might take through the rock cycle:

Magma is erupted out of a volcano and becomes lava. The lava cools quite quickly and becomes an extrusive igneous rock. The extrusive igneous rock is broken down over the next 10,000 years and becomes sediment. This sediment is gradually blown into a river where it is washed into the sea. This sediment joins up with millions of tonnes of other sediment and gradually through the process of compaction and cementation becomes sedimentary rock. Over the next million years this sedimentary rock is forced deeper into the earth and undergoes immense heat and pressure, this eventually turns the sedimentary rock into metamorphic rock. Another million years pass, and this metamorphic rock melts again and changes back into its original state of Magma.

Properties of Rocks

Weathering

Physical Weathering

Freeze Thaw

Freeze-thaw weathering happens in cold areas where ice can form. A crack or weakness in a rock can fill with water which then freezes as the temperature drops. As the ice expands, it puts pressure on the rock and pushes the crack apart, making it larger. When the temperature rises again, the ice melts, and more water fills the larger crack. The water freezes again as the temperature falls, and the expansion of the ice causes further expansion to the crack. This process continues to happen over and over again until the rock breaks.
Exfoliation (onion skin)

Exfoliation is a process of weathering that occurs in areas that experience large changes in temperature on a regular basis, for example deserts that are cold at night and incredibly hot during the day. During the extreme heat rocks expand slightly. Then, during the colder nights rocks contract again. This expansion and contraction of rocks causes the outer layer of the rock to peel away from the core of the rock, just like the layers of an onion.

Biological Weathering

Living organisms such as plants, trees, animals, mosses and people contribute to the weathering process in countless ways:

Tree roots grow and extend through joints or cracks in rocks in order to find water and nutrients. As the tree grows the root systems grow also. The roots gradually push the rocks apart and cause them to breakdown and split.

Animals and humans damage and wear down rocks over time by moving across them, a good example of this is footpath erosion. Animals specifically also cause biological weathering through acts like making dens and burrows.

Mosses and lichens that grow on rocks can also damage the surface layers of rocks by altering the PH balance and causing chemical reactions.

Chemical Weathering

Carbonation (acid rain)

Carbon dioxide gas from the air dissolves in rain to form weak carbonic acid. This very slowly eats away at certain rocks, often creating spectacular features such as stalagmites and stalactites. Carbonation creates what is known acid rain, acid rain is not harmful to humans.
Oxidation

Also known as ‘rusting’, this occurs when oxygen and moisture mix with minerals which contain iron. Oxidation is accelerated (made faster) by moisture and high temperatures.
Hydrolysis

Water combines with some minerals in rock and turns them into clay making it easier for them to be washed away.

Limestone Landscapes

Karst Landform Formation:

Acidic rain falls to the ground. The acidic water then flows over limestone bedrock, this creates weakness in the bedrock.

Water then exploits these newly formed weaknesses in the bedrock and flows through the rock quicker and with more force. This creates underground drainage routes.

Over millions of years the surrounding rocks are eroded further, creating underground rivers and swallow holes.

Along with these features we also see the formation of stalagmites, stalactites, sink holes and limestone pavements.

Millions of more years pass and we see the formation of karst topography and limestone mountains.