I was out this morning scouting some sites for a field trip related to ophiolites. Naturally it focused on those strange and unfamiliar rocks that most people never heard of: peridotite, serpentinite, greenstone, gabbro. On a whim (well, to check my tires) I visited one last roadcut and stared at the dark gray stone there, shot with carbonate veins and blocky fractures. "Are you metabasalt?" I asked it. Sometimes that helps, though not always right away. After a while I said, "No you're sandstone, aren't you." I had my eyes open for ophiolite, not sandstone. But that's what it was; specifically it was graywacke. A familiar rock, but with a strange name.
With the Thanksgiving holiday coming up, expect Plymouth Rock to take its regular turn in the spotlight. Supposedly the landfall of the Pilgrim colonists in 1620, the rock is rather more fragile than is suggested by its iconic character. In my discussion of the rock I note that having been carried to Plymouth Beach by the glaciers (and thus qualifying as an erratic), it was probably damaged in transit. Reader Walter Handy, who studied geology nearby, says that the beach is eroding its way through a drumlin and is littered with bouldersso let us add marine erosion to the rock's history of insults. The topographic map of Plymouth doesn't show classic tapered drumlins, just lumpy, poorly organized ground, so maybe the rock was eroded out of ground moraine. Either way, Plymouth Rock was ridden hard and put away wet, as the saying goes. Neither could the added stress of celebrity, so well documented in humans, have helped Plymouth Rock in maintaining its integrity.So now I'm exploring what exactly people mean by Earth science as opposed to geology. My first thought is that geology is whatever people did up to plate tectonics and Earth science encompasses the new jobs and tasks that have arisen since then. So prospecting, mapping, fossil studies, site investigationthat's geology. Water supplies, waste disposal, mine remediation, climate changethat's Earth science.
But I'd like your ideas.
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