Mudstone (Shale)
What is a mudstone?
Mudstone is a sedimentary rock made of very small particles of mud and clay – it is “fine-grained” and often called shale. They occur a lot in the Carboniferous period in cycles with sandstone, limestones and coals.
How do I recognize it?
Mudstone is often very soft and breaks up easily. They are usually black or dark grey in colour.
Where do I find it?
The best places in Northumberland are places where rivers or the sea are actively eroding banks and cliffs. Because they are so soft mudstones doesn’t survive very long in the open.
How was it made?
They form when mud and clay particles are deposited by water. The tiny particles settle slowly to the bottom of oceans, lakes, or even in quiet rivers. Because they are formed in gentle conditions mudstones often contain fossils of delicate things like fish and plants.
What does a mudstone landscape look like?
Because they erode so easily the low ground and depressions between ridges of harder rocks are often areas of mudstone.
Which plants like mudstone?
Plants which like ill-drained soils, like rushes and meadow sweet, because mudstones tend to hold the water and are not very permeable.
What use is it?
Mudstone is often used as a raw material for making bricks and pottery and because it is found along with coal there is a source of heat to fire the kilns.