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paleoexplorer
Notice the dark areas of the root on this #megalodon #shark tooth. That was the only thing exposed on the river bottom. The rest of the tooth was pointing straight down in matrix and gravel. I found this tooth while #scubadiving the black water swamps of #Virginia
Sunset Over the Blue Ridge Mountains, Buena Vista VA - May 2019
This massive thunderstorm provided hours of stunning moments from this apocaliptic sunset shot to constant lighting strikes visible after dark.
North Mountain/Pete’s Cave
Rockbridge County, Virginia.
Autumn Story.
Falls Ridge Preserve, Virginia.
A geologist's breakfast? Fry ups are an essential part of field cooking, where getting plenty calories in with minimum time and effort is a way of life. These amazing speleothems called fried egg form in caves when slightly acidic water is forced to precipitate some of its mineral content (in this case calcium carbonate deposited as calcite) when it encounters a change in conditions. This particular example is from Luray Caverns in Virginia and could be a wonderful way to start one's day spelunking. Loz Image credit: Abraham S
As the stormy weather exists.
From the Blue Mountains of Virginia.
Weather’s getting warm and I can’t wait to return to the Virginia Creeper Trail! It’s a 34 mile railroad-turned-bike trail through Mount Rogers National Recreation Area and gorgeous Virginia farmland. We typically bike from Damascus up to Whitetop Station (or as close as we can get, it’s a hard climb!) then coast back down the hill enjoying the scenery.
Sometimes It Snows In April.
Blue Ridge Mountains, Virginia.
A Springtime Scene.
- From the mountains of Virginia.
Jefferson National Forest, Virginia.
A Fiery Appalachian Sunset.
As The Water Flows.
Arcadia, Virginia.
Up on the Parkway
Virginia
Night hikes are the best hikes.
Devils Marbleyard, Virginia.
Fairy Stone Park
The story of these little crystals begins over 500 million years ago as sedimentary rocks were deposited along the coastline of a continent we call Laurentia – predecessor to modern day North America. Those sediments were deposited in a passive margin – an area with no active continental boundary, formed when the supercontinent Rodinia rifted apart to form a new ocean. 300 million years ago or so, that ocean closed as what is today Northwest Africa collided with eastern Laurentia, uplifting a huge mountain range. The sediments that were originally deposited off the coast of Laurentia were trapped in this mountain range. They were shoved deep into the Earth’s crust and heated, so much so that the minerals in the rock changed – making the sediments into a metamorphic rock.
One of the metamorphic minerals produced under these conditions is the mineral staurolite. Staurolite has a neat property to its structure called twinning – the layers of atoms that make up the mineral will sometimes shift along a plane or surface inside the mineral, and they do so in specific patterns. Staurolite twins by creating either 60 or 90 degree angles inside the crystal – basically forming two crystals that interlock, into a cross shape.
These staurolite crystals grew during the metamorphic event caused as the Appalachians formed. Eventually Africa and North America separated and these rocks were pulled back to the surface by new faults and erosion of the mountains above. As they cooled off, the staurolite converted to sericite, a lower-temperature mineral, without changing shape – a process called pseudomorphing (one mineral in the shape of another).
Given the religious significance of the cross shape, and the fact that they’re just neat in the first place, it’s not hard to see why these stones became collectable. Even imperfect stones can be used – the sericite is soft enough to be easily cleaned and polished and shaped into perfect crosses. In fact, I even found a literature reference from 1934 of one of them being polished into a Swastika. These stones are picked out of Fairy Stone State Park in Virginia – they are free to collect as long as you use only your hands and pay admission/parking fees in the park.
-JBB
References: http://www.dcr.virginia.gov/…/blog/legend-of-the-fairy-stone http://www.minsocam.org/ammin/AM19/AM19_549.pdf
