How limestone formed.

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How limestone formed?

Most limestones in our part of the world formed in

shallow seas that covered our area hundreds of

millions of years ago.

Other names for limestone

We use the scientific name "limestone" for this rock,

but it is also known by many other names:

When limestone is crushed into gravel and

used for building roads or making concrete, it's often called an aggregate.

Here are some ways to classify limestone (by grouping it with similar types of rocks):

Geologists have a catch-all term that includes both limestone and dolostone. They call them carbonate rocks.

Limestone is a sedimentary rock.

How to recognize limestone

Limestone is mostly light to dark gray in color.

Its grains can be mud-sized, so that the rock looks dull, or they can be sand-sized or larger bits of broken shell or other limey material.

You can scratch limestone into white powder with a nail or knife. (See more about the scratch test.)

Limestone is made mostly of the mineral calcite, so it bubbles gently when you put a drop