The story behind your driveway gravel

The US produced more than 1.4 billion tons of crushed stone in 2020.


Quarries keep us going.

There are thousands of quarries all over the United States, and they are crucial to our day-to-day lives. By breaking up rocks, then crushing and sorting them, quarries provide rocks for our homes, businesses, roads, landscaping, sidewalks, and much more! The picture above is from a limestone quarry.

Chances are there is a quarry within 25 miles of your house. Because rock is really heavy, the cost of getting it increases greatly with distance. After all, dump trucks use lots of fuel! You can use Google Maps to find quarries in your area. Look for them just outside of town near major roads.




Last week I visited a local limestone quarry with a science camp. Limestone is a sedimentary rock that is formed under water and made from minerals of calcite (calcium carbonate). Look at the quarry wall to see the sedimentary layers.

Crushed Stone

After blasting (see video below), the rock is fed through crushers and conveyors to break and sort the rock into different shapes. We are standing next to a pile of #57 rock, which a mix of rock from 0.75 to 1.5 inches across and a common size used in roads and concrete.

And Fossils!

Some of the layers of limestone in this quarry also contain fossils. There are brachiopods with their two shells, circular crinoid stems, coiled nautiloids, and horn corals like the two in this specimen.


From "boom" to ballast in seconds

Quarries begin by blasting rock with explosives, or what they call a "shot". A hole is drilled down into the rock to place the explosives. The detonations are timed fractions of a second apart from each other. This better fractures the rock and keeps it from flying dangerously far. Once the dust settles (literally!), the trucks move in and begin scooping, loading, and adding stone to the crushers. It's a pretty impressive turnaround.

Check out this great video that shows the real-time speed and then slow-motion of a quarry shot in Ireland.

And if you want to learn more about the fascinating rocks, minerals, and fossils of God's world, check out our Geology page!




Many Blessings,

Marcus R. Ross, Ph.D.

 Science, Faith, and FUN!!!

  • Jul 21, 2021
  • Category: Geo-Bytes
  • Comments: 0
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