Bedding
Bedding planes are only found in sedimentary rocks. They are the flat surfaces that were originally parallel with the surface on which the sediment was deposited e.g. the sea floor, the river bed
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Chemical weathering
Erosion as a result of a liquid ( usually rain water) flowing over a rock causing a chemical reaction that dissolves the rock's minerals and washes them away. For example, acid rain dissolves calcium carbonate out of the limestone. The resultant water is calcium carbonate rich and can be deposited as calcite elsewhere e.g. as a stalactite in a cave.
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Erosion
The wearing away of the land surface by grains of sand, silt etc propelled at force by a natural process e.g. wind, water, gravity, ice. For example, pebbles carried by a fast flowing river will have significant force to erode the river bed. If you have walked along a sandy beach in the strong wind you will have felt the force of wind erosion on your face!
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Gangue mineral
The mineral from which a mineral/metal of value is extracted. For example, galena (lead sulphide) is the gangue mineral for lead.
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Loess
Wind born dust derived from rock exposed around ice sheets during the Ice Ages.
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Mineral
A naturally occurring solid of definite chemical composition e.g. calcite. N.B. there is one liquid mineral - mercury.
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Permeable
This is a measure of how quickly a liquid can flow through a rock. It is an important property to consider e.g. when building a reservoir, when sourcing new oil reserves.
Liquid can flow through a rock in two different ways:
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Through pores or small inter-connected holes (like a sponge) in the rock's structure i.e. it is porous
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Through joints and cracks in the rock i.e. is it pervious
Peak District gritstone has many holes within its structure that allow it to hold water and so is considered to be porous. However if the pores are not well connected then liquid cannot easily flow through the rock and so will not necessarily be highly permeable but more impermeable. Peak District limestone is very jointed and cracked and therefore considered to be pervious.
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Resistant
A rock that is able to withstand erosion relative to others in considered to be resistant. Gritstone is comparatively more resistant to erosion than shale.
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Rock
Rock is a hard natural substance made up of one or more minerals. e.g. limestone.
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Sedimentary
These are rocks formed from sediments. Limestone and gritstone are examples of sedimentary rocks in the Peak District.
Sediment can be made up of organic material (plant and animal matter) and/or silt, sand, mud etc. Silt, sand and mud themselves are formed by the wearing away of other rocks, for example by wind or water.
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Tectonic
This refers to large scale movements of the earth's crust causing pressure changes, often resulting in volcanic or seismic (earthquake) activity.
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