Showing posts with label Rocks. Show all posts
Showing posts with label Rocks. Show all posts

Wednesday, September 28, 2011

Exploring An Ancient Cave


There are a lot of things I want to do “someday.” One has been exploring an ancient mine on Mount Jasper in Berlin, NH. Long-postponed somedays are here now since I decided last spring to cap my teaching career at thirty-six years. So, a couple of weeks ago my wife and I climbed to the top of Mount Jasper’s southwest-facing cliff, then carefully threaded our way down to an old cave. It’s a man-made cave that took thousands of years to hack into a seam of multi-colored jasper. The material is also called rhyolite and it threaded diagonally up the exposed ledge of the mountain after forming over a hundred million years ago.

For years, I’ve been finding stone artifacts and flakes left by prehistoric inhabitants of the Fryeburg area, many of which I noticed were made from distinctive kinds of stone. Online, I learned some of it was a material called rhyolite from a source near the upper Androscoggin River in Berlin. Available evidence indicates that early Americans discovered it there and have been extracting tool-making material from this cave for about nine thousand years.Berlin from the ledge above the mine. Rain shower coming in from the south.

The first I’d learned of the mine was in a column by Ed Parsons in The Conway Daily Sun back in 1998 or ’99. Parsons writes mostly about hiking, and it seems he’s been up nearly every hill and mountain in the area. Included was a photo of the City of Berlin taken from top of the ledge above the mine. That’s when I made up mind to go there someday and check it out.

Two things made this a trip my wife and I could enjoy together: one - it involved rocks, which we both like. Two - it involved hiking, which isn’t one of my passions, though I do it occasionally because she likes it. “Just to get to the top” doesn’t motivate me to walk up up a steep hill for hours. If there’s a pegmatite mine on top, that would be some incitement, but that kind of mine is common in this part of the world and there are many I can drive to. If there were old cellar holes to examine on the way up a hill, that would motivate me too, but if there’s just a nice view, well, there are lots of nice views around I could drive to and enjoy with a sip of wine without getting all tired and sweaty climbing up and down. The historical significance of the Mount Jasper mine, and that it’s one of the oldest human-made sites in the whole northeast, excited me greatly and it was only about a half-hour hike up. All that put it near the top of the bucket list for this retired history teacher.

I researched it as much as I could before going, of course, and learned that ancient Americans probably didn’t spend a lot of time on site. Evidence uncovered thus far indicates that they went to replenish their tool supply. They would chisel pieces of jasper/rhyolite out of the cave, lug them to the top of the ledge or down to the bottom near the Dead River, and begin working them into tools like spear points, arrowheads, knives, scrapers and drills. Sometimes they would make cores, or rough chunks, which they would lug back to their settlements to further knap into the finished tools listed above. The flakes I found in Fryeburg were a result of this process.Close match. The one on the right was found at the entrance to the cave. The two on the left I found in Fryeburg.

Those who made finished tools there would sometimes discard their worn-out knives or arrowheads made of stone they’d gotten elsewhere in the northeast - like Mount Kineo or Munsungan Lake, Maine. These were found in the two working areas above and below the mine, which were partially excavated by Archaeologist Michael Gramly, whom I’d had the good fortune to meet and talk with for hours while visiting in Oquossoc, Maine. He strongly encouraged me to make the trip to Mount Jasper.Different facets show different effects of weathering as rhyolite chunks have been chiseled away over time.

When first glimpsing the entrance to the cave we noticed pieces of rhyolite strewn about and exposed to the elements. Material on the walls of the mine inside was not weathered and showed different colors ranging from red, blue and green to gray. I’d found both weathered and unweathered artifacts and flakes of Mount Jasper rhyolite in Fryeburg, and I’d carried some to the mine with me for comparison.Close-up of image above. It's a pretty rock.

I shouldn’t have been surprised that the rhyolite would change its appearance after weathering. Old stone walls turn gray after little more than a century while newly-dug-up stone looks distinctively different and contrasts older stones when added to an already-existing wall. Some of the rhyolite artifacts I’ve found had been laying around a long time. Others seem to have been covered by soil shortly after the knapping process and retained their fresh appearance. I found these latter while examining freshly plowed and harrowed fields after a rain.Mount Jasper cave ceiling

In my research, I learned there’s another, even older site near Mount Jasper in Jefferson, NH where a similar kind of rhyolite was being knapped twelve thousand years ago. The “someday” I explore there will likely arrive later this fall.

Saturday, September 25, 2010

Rocks

I like rocks. Always have. They're solid. They're old. Each one has a story millions, even billions of years old. If I see an interesting rock small enough, I'll sometimes take it home. If it's too large, I'll photograph it.Saw this one on a hike up Whiting Hill in Lovell, Maine last week. It's white quartz with light brown feldspar - pretty typical for a hilltop in western Maine.Here it is closer up. The black outline of weathering around the crystals pleases me.Like to climb over rocks too, especially along Maine's coast. This is part of the bedrock near Biddeford Pool on the southern Maine coast. Maine has some of the most varied geology to be found anywhere on earth. It's not only interesting; it's beautiful. The amateur geologist in me thinks this is sedimentary, metamorphic, turned up 90 degrees and weathered by the surf.This is just a few yards away, but from another age entirely, and that's how Maine bedrock is. This rock heated and swirled more than the one above it.Only about four feet away is this one in a seam where iron oxidized, creating dark red staining.Looks like chemical reactions I don't understand at all are creating different textures as well.Albany, Maine stone wall I found in an abandoned neighborhood last spring.Carrickabraghey Castle on Isle of Doagh, Donegal where we visited two years ago. My ancestors built this "keep" - all that remains of the 14th century castle that was about ten times bigger than what you see here.It's mostly limestone around that area, but some granitic outcrops are scattered about. Glashedy Island is offshore. Glashedy means "green on top." It's a big rock with ten acres of grass on it. Locals brought sheep out there to graze.View out to sea from inside the keep. I love the way the limestone weathers inside - so different from the granites and feldspars of Maine. Easier to work as well.View out another window.And another.And out a door with my wee wife outside.And a high window.A long beach nearby deposits weathered rocks in terraces. When waves recede, millions tumble against each other. The sounds they make are as charming to the ear as the polished limestone specimens are to the eye. The wee wife has found a beauty to smuggle home. Ireland won't miss it.