Sandstone vs. Limestone, a Dummy Comparison

sedimentary rocks

One of the Antisocial Network staffers briefly wrote for the folks at eHow.com before she got tired of the politics of the site. She freely admits to having used a nom de plume, as did many of the site's contributors. Hers, at least, was a reasonable facsimile of a real person's name... which is not the case of today's nominee. No, that worthy chose to call herself Sancho M. Panza. We don't know if "Don H. Quixote" was already taken, but can't help but snicker. We also snickered when we saw what this person did to the Sciencing.com post, "What Is the Difference Between Sandstone & Limestone?"

As is the case of many eHow/Sciencing posts, Panza's attempt to answer the question is a pastiche of semi-related factoids. In assembling her collection, Sancho M. managed to make a few mistakes, misstatements, and downright screw-ups. We'll address a few, just for the fun of it:

• "Limestone is defined as being primarily composed of calcium carbonate, which often comes from plant and animal material such as the shells of mollusks." — Just mollusks, Sancho? No brachiopods, corals, bryozoans, or crinoids? 
• "Sandstone is formed from the breakdown of larger rocks due to weathering and erosion as well as from processes that occur within the rock, usually biologic but sometimes chemical in nature." — You already said that when you mentioned weathering. We would be remiss if we did not point out that "biologic processes" are not at all important, you idjit.
• "Most limestone beds form in marine environments..." — We know of no limestone that formed in a terrestrial environment, Sancho.

• "Sandstone is often classified based on the type of grain it contains in large quantity. For example, ferriginous [sic] sandstone denotes a high iron content." — Umm, no, ferruginous denotes a sandstone cemented with iron-rich minerals; not one with "high iron content."
• "Limestone may be informally described by the type of carbonate it contains, such as calcite, aragonite and dolomite." — Ummm, no, it's not. Limestone is classified on the basis of texture. That, and dolomite-rich carbonate isn't limestone, it's dolostone. We've also never heard of a rock called "aragonite," which is a mineral.
• "Many sedimentary rocks, such as sandstone, display a visible stratification into layers. This distinct pattern can help determine how a rock was formed based on the angle and depth of each layer." — A study of the geometric relationships of multiple layers can help determine genesis, but "angle and depth of each layer"? That doesn't even make grammatical sense

Suffice it to say that few, if any statements in Sancho's post were correct as a whole, and most were just plain silly. Small wonder our Dumbass of the Day pretended she was the squire to the Man of La Mancha...

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