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Geology/Differentiating Limestone


How does one differentiate between Cambrian Limestone and Jurassic Limestone?

The two are from different geologic periods.

The Cambrian Period was very early in the Earth's history:

You have the very early earth, the Pre-Cambrian era, followed by the Paleozoic era that was divided into the following periods: Cambrian, Ordovician, Silurian, Mississippian, Pennsylvanian, and Permian.
The Mesozoic era was divided into the Triassic, Jurassic, and Cretaceous periods. Contrary to the movie, the dinosaurs mostly lived in the Cretaceous period.  But "Cretaceous Park" just does not have the same ring to it.

The Cenozoic Era is divided into Paleogene, Neogene, and Quaternary, which is what we are living in.

Now, as you can see, there were a lot of periods between Cambrian and Jurassic.

Cambrian was about 650 million years ago.  Jurassic was 180 million.

Now depending on the thickness of the limestone formation it could have take many millions of years for the limestone to form, depending on the type.

Many very pure thick limestones were laid down in the deep ocean.  These are associated with quartz nodules.  Still others were laid down in shallow seas like the one that covered the middle of the US and laid down the limestones found in Oklahoma, Kansas and other midcontinent states.  We call these differences, depositional environments.

As to how to differentiate them.  Fossils help.  Cambrian limestones will have fossil marine shell animals, with Trilobites dominant.  Jurassic limestones contained the first primitive bird and mammal fossils, dinosaur tracks, and fossilized ammonites (the long cone shaped relative to the chambered nautilus).

Hope this helps.


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Keith Patton


I can answer questions concerning physical and historical geology, environmental geology/hydrology, environmental consulting, remote sensing/aerial photo interpretation, G&G computer applications, petroleum exploration, drilling, geochemistry, geochemical and microbiological prospecting, 3D reservoir modeling, computer mapping and drilling.I am not a geophysicist.


I have 24 years experience split between the petroleum and environmental industries. I have served as an expert witness in remote sensing, developmental geologist, exploration geologist, enviromental project manager, and subject matter expert in geology and geophysical software development.

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