Discovering Where Your Gravel Comes From
Gravel is a material that many people, not in the construction industry, rarely think of. We use it to build houses, pave roads, and even filter water through it. But the question is, where is it found and how do we make it? It’s a question that not too many people have considered, but it’s one that is worth answering to better understand what makes this common material so unique. In this blog, we’ll take a look at the basics of gravel to help you understand where it comes from and how it’s used.
What is Gravel?
Gravel is a collection of loose material that’s made up of rock fragments. The most common types of stone found in gravel in the UK are Limestone, Granite and Sandstone.
Gravel is classified by a particle size range and includes size classes from granular to boulder sized fragments. It is graded as fine, medium and coarse, with ranges from 2-6.3mm up to 20-63mm.
What is Gravel used for?
Gravel is used in a wide range of industrial and construction applications, from home building to road paving.
It is estimated that almost half of all gravel production is used as an aggregate for concrete. A lot of the rest is used for road construction, either in the road base or as the road surface itself.
The different types of Gravel
There a two types of gravel, Man-Made and Naturally formed.
Man-Made Crushed Stone:
By the simplest definition, crushed stone is exactly as it sounds, stone that has been crushed. Most crushed stone is produced in quarries by mining larger stone and using machinery to break it up and crush it. Instead of being shaped and formed naturally, crushed stone is produced with man-made machinery and procedures.
Naturally Formed Gravel:
Naturally formed gravel is similar to crushed stone because it is a type of rock, but it’s produced naturally. It is usually found next to rivers and streams and commonly has a smooth surface due to being exposed to the natural effects of running water.
How is my Gravel stone formed?
There are many different formations of stone/rock that are found in, or made into, Gravel form.
Igneous rocks such as Granite and Basalt, are formed after molten rock or lava solidifies.
Sedimentary rocks such as Limestone and Sandstone are formed over time by the accumulation of small particles becoming cemented together. This piecing together of the rock often produces layers in the rock.
Metamorphic rocks such as Marble and Slate, become changed through intense heat or pressure, similar to clay hardening in an oven.
Where in the UK are the different types of stone found?
Limestone is a sedimentary rock formed by the accretion of skeletal fragments of marine organisms such as coral and shell.
The UK has a wealth of Limestone deposits and is sourced mainly from the southern half of the British Isles, however there are also a few quarries in North.
Limestone in the UK can be found in various colours such as Beige, Blue/Black, Grey and Pink.
Sandstone is a sedimentary rock that consist mainly of sand-size grains bonded together by interstitial chemical cement.
The UK has an abundance of Sandstone sourced mainly from the northern half of the British Isles and deposits are found in South Wales.
Sandstone in the UK is available in various colours such as Red, Pink, Brown and Pale Buff, Blue/Grey.
Slate is a metamorphic rock that is formed when shales and clays are put under great pressure and heated inside the earth for millions of years.
Slate is found in Wales and the North-West of England. You will find the majority of UK slate mines in Cornwall and in the Lake District in Cumbria.
Slate in the UK is usually found in colours of Black, Brown, Grey, Blue, Green and Plum.
Granite is an igneous rock that forms when magma cools relatively slowly underground.
The principle Granite quarries can be found mainly in the South West of the UK in Devon and Cornwall. Some small deposits can also be found in some Northern regions such as Cumbria and Leicestershire.
Granite in the UK can be found in the colours White, Grey, Brown, Beige and Black.
Flint is a hard, tough chemical or biochemical sedimentary rock. It is a form of microcrystalline quartz that is typically called chert by geologists.
Flint is most commonly found across southern and eastern England and also Norfolk.
Flint in the UK is found to be grey, black, green, white or brown in colour.