Fossils and Sedimentary Rocks for Dummies

Coquina (fossil conglomerate)

We long ago lost track of the number of times we've run across would-be freelancers who pluck some unfamiliar factoids from a reference somewhere and run with them. If you're even moderately familiar with the field, you might find it amusing... except that somewhere, some poor student is probably trying to convince a teacher that the "research" they've cited is sound. Here's an example: somebody googled (or Binged, whatever) the homework question, "Fossils Are Most Common in Which Rock Types?"¹ and eHowian Esperance Barretto figured, "How hard can that be to answer?" Based on what she wrote at Sciencing,com, it was a lot harder than she thought.

In reality, the answer consists of just one word: "Sedimentary." Barretto managed to spit that out, gilding that particular lily with the information that,

"Fossils cannot survive the elevated temperatures and pressures through which igneous and metamorphic rocks are formed."

Apparently, Esperance didn't seem to realize that she should have been talking about the plants and animals whose remains become fossils, not the fossils themselves... guess U of Mumbai doesn't require their English Lit students to take Rocks for Jocks, eh?

Sadly, Barretto knew she wouldn't get paid if she limited her "answer" to one word or even the sixteen above; she needed 300-500 words. It's in the other 300 or so words that we found Esperance babbling incoherently. We're talking claims like,

• "Limestone, sandstone, shale and conglomerate are some of the sedimentary rock types that contain fossils." –  No, Esperance, conglomerates don't contain fossils.
• "Limestone is generally found in warm, shallow marine waters like reefs." – No, Esperance, limestone is generally formed in shallow marine environments. It's found just about everywhere... including above the Arctic Circle!
• "Sandstone is formed in diverse environments where huge quantities of sand accumulate as a result of water or wind movements. It is generally found in rivers, beaches, flood plains, deltas, oceans and deserts."  – Again, those are the places where sandstone forms. And while we're at it, "desert" means dry, not sandy!
• "Sandstone can be layered in different colors, as a result of the fossil deposits." – Sorry, Esperance, the color is not a result of the fossil species present. And while we're at it, sandstone is much less likely to be fossiliferous than  limestone or shale because the energy necessary to move the sand grains chews up bones and shells.
• "Shale is a finely textured sedimentary rock..." – She means "fine-textured."

Barretto went on to reword some reference she found expounding on the geology of Canad's  Maritime Provinces, incorrectly claiming that,

"...numerous marine fossils [occur] in the conglomerates of Canada’s Western Newfoundland and southeastern Labrador Peninsula..."

The actual reference says, "conglomerate, limestone and marble, sandstone, shale and slate." Such is the folly of attempting to reword something you don't understand... unless, that is, you want to be named the Dumbass of the Day (like Barretto).

¹ The original has been deleted by Leaf Group, but can still be accessed using the Wayback machine at archive.org. Its URL was   ehow.com/info_7839677_fossils-common-rock-types.html

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SI - PALEONTOLOGY