Saw this beauty on a field trip Saturday, examining the glacial geology of western Pennsylvania. Note the faceted surfaces and profusion of scratches of multiple sizes in multiple orientations.
Saw this beauty on a field trip Saturday, examining the glacial geology of western Pennsylvania. Note the faceted surfaces and profusion of scratches of multiple sizes in multiple orientations.
Awesome pencil/scale combo! (NOTE: I live on Long Island, so that’s why I was more excited about the pencil than the cobble)
I got it from Little River Research and Design. Check it out!
Nice specimen! Not to be a party pooper, but I think it’s worth a note of caution to any casual rockhounds or students who might see this photo and think that any cobble with scratches is automatically displaying glacial striations. Context is everything: if I found that cobble embedded in an undisturbed gravel exposure, or indeed, lying at the toe of an actual glacier(!), I’d say “for sure”. But if I found it lying loose on the floor of a gravel pit, or on the shoulder of a country road, or in a farmer’s rock-pile, I’d say “maybe”. A lot of convincing-looking scratches are generated by bulldozers, graders, cultivators and other heavy machinery. Likewise, if I found it in Florida, I’d also tend to err on the side of skepticism!
Cheers
Excellent point. Thanks, Howard.
Thanks for the clarification Howard, i was actually about to ask how to determine whether or not the scratches were caused by a glacier…