Thursday, November 27, 2008

It's the Rocks That'll Kill You

I've always assumed that the horrific casualties sustained by both armies in the American Civil War resulted from the collision between new military technology - mass-produced rifles and minie balls - and outdated, offensive-oriented tactics. However, geologists Judy Ehlen and Robert Whisonant report that geology and topography may have also played roles in generating the conflict's high body count. Battles that took place above limestone, for instance, tended to be very bloody because limestone erodes quickly, creating "flat, open terrain" and ample fields-of-fire for riflemen. Such was the case in Miller's Cornfield at the Battle of Antietam (17 Sept. 1862), where 8,000 men were killed or wounded in just a few hours, and during Pickett's Charge on the last day of the Battle of Gettysburg (3 July 1863). Conversely, battles fought on dolomite or shale, like the firefight at Burnside's Bridge across Antietam Creek, tended to have lower casualties because those substrata produced more rugged surface terrain, screening attacking soldiers from defensive rifle fire. Whisonant and Ehlen determined that 25% of the war's deadliest battles took place on terrain with a limestone base - certainly an important factor in determining casualties, if not a predominant one. (Source: The Chronicle of Higher Education, 21 Nov. 2008; see also here and here.)

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