Thanks for the comments and the rabbit hole of local geology. Blogbuddy Paul emailed these
based on the post from last night.
An explanation and
illustrations from Eric Sloane << (another rabbit warren to explore)
It's amazing what the settlers did around New England. All by hand and horse and oxen.
I searched various terms of Schists and Gneiss and New England Geology and came across
some interesting information including this post when I was researching Eric Sloane:
Stonewalling
If you enjoy a stroll through the woods in New England, you will likely
find stone walls. A very short moment in each year is the harvest.
Mechanized now, the harvest was once a near-panicked and frantic race
for many seasons. Making hay is even a risky venture with New England
weather. I occasionally bird hunt in up-state New York amongst the
cleanly-shorn fields where some of the migratory birds glean the errant
grains from the ground.
This is long list of the various "rocks" around here:
The USGS has a list of all the "Geologic Units" in Rockingham County <<<
Another site describes in detail how the stone goes from Shale to Gneiss:
Tectonic forces transform dull mud to dazzling schist
Schist is a metamorphic rock, and it started out as a different kind of stone before it became so sparkly and awesome. In fact, schist was boring mud before metamorphic forces got to it. If you compress mud (underneath the weight of the ocean and a whole lot of other mud) you get shale. If shale gets buried deeply, compressed, and heated it will turn into slate, which is denser and harder than shale. If the heating and compression increase, the slate will become phyllite, which is a shiny version of slate. Phyllite has a subtle shine because the original clay minerals in the shale have transformed into small mica minerals. If phyllite remains in the geologic pressure cooker, the mica minerals grow larger until they are glitter-sized. Voila! We have schist.
My interest in exploring the plethora of rocks around here has been enhanced by yesterday's find
and the comments from the readers. Thanks!
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| https://pubs.usgs.gov/of/2003/of03-225/fig1.html |
One last rabbit warren for today....
Volcanoes of New Hampshire<<<<
Eric Sloan's books are awesome. They're windows into colonial New England. Some of the illustrations have helped me solve problems on my farm in Pennsylvania.
ReplyDeleteOn the rock walls in NH. When I first started hunting, my Dad told me that if i ever got lost in the woods to keep walking until I came to a stone wall. Then pick a direction and walk along the wall until it came to an old road. It would eventually he said. Once the road was found, again pick a direction and walk along until you either came to a tar road or someones field with a house and/or barn. I put that theory to the test on my first excursion into the Maine woods around camp. It worked, although I ended up about four miles and on the wrong side of the mountain from camp. Never made the mistake of going into the woods without a compass again. Dad was not to happy with me as my brother, who was with me, and I arrived at camp well after dark.
ReplyDeleteFunny thing was a couple weeks later Dad and his hunting partner for the day, made all of the same mistakes my brother and I made and ended up at the exact same farm on the wrong side of the mountain. They had a compass with them, but didn't believe what they were reading from it.
Nemo
Most people don't know that New England was once almost totally denuded of forest by the early 1800's from the White Mountains to the CT/RI coast and west to the western border of NY. The trees were used for building log homes and milled lumber houses and barns and firewood.
ReplyDeleteOn the stones. The field up at camp yields a new crop of tennis ball/baseball/softball and sometimes bigger sized stones every year. Raises hell with the mowing machine. They get pushed up by the winter freeze/thaw cycle. That field is probably two hundred or more years old and it is still puking up stones left behind by the glaciers that covered the land 10,000 years ago. The stone walls along the property lines are waist high and two stones thick, all roughly the same size at 30" to 24" long by 15" to 10" wide and 10" to 6" thick. They all look like granite.
Nemo
Schist is what all the high rises in NYC are built on it doesn't exist in most of the burroghs so you won't see them there. Saw it on a secrets of new york documentary. Mother Nature is mighty and magnificent. My home state, supposedly, has what would have been the tallest oldest mountains in the world till they fell over. The diagonal display with some soil on top looks like row planted rocks. You can see them here
ReplyDeletehttps://www.pinterest.com/pin/385480049326631279/
and read about it here.
https://www.nps.gov/chic/learn/nature/geologicformations.htm
Eric Sloane would often autograph his books and leave a little drawing on the frontispiece. Keep an eye out for that if you find his book in a used bookstore.
ReplyDeleteInteresting, but it leaves out one thing. The reason there are lots of stone walls is that they were too heavy and too many to move any further.
ReplyDeleteAs an old geologist girlfriend used to say…Schist happens.
ReplyDeleteLook for lightning striking the same place, might find something like this one found about 2 miles from where I grew up:
ReplyDeletehttp://www.geo.mtu.edu/KeweenawGeoheritage/CalumetGeosites/Float_Copper.html
When you get out of Boston proper, by 15 miles or so, the woods all have stone walls. Amazing to see when you are a kid. The rate of reforestation in rural New England is enormous.
ReplyDeleteSpeaking of, on the coast of Maine, when you can find a piece of bedrock that isn't full of fractures from ice damage, you can see deep scrape marks from the glacier passing over the bedrock. They all run a little south of east. Better than a compass. The older blueberry barrens in downeast Maine all have outcroppings of scratched bedrock.
there is a place in western MA called Burnt Hill. apparently there are random rock walls that predate european settlers.
ReplyDeleteoh, and a stonehenge.
https://www.atlasobscura.com/places/burnt-hill-stone-circle
Never got that far east, but in the woods of SE Ohio you might find "Indian Trees." They were once saplings, bent over as path direction markers by the natives, and kept their j-shaped bend over the decades.
ReplyDeleteThat was a fascinating trail to follow.
ReplyDeleteI have a copy of Eric Sloane's book A Reverence for Wood. An informative read with great illustrations.
ReplyDeleteTook a trip to Door County Wisconsin and was amazed at the amount of rock walls (2-3 feet high)
ReplyDeleteI can't believe so many people all thought (hey, this looks like a great place to plant stuff"
Out in the Fly-Over, it is loess or clay over limestone. Some of the river-rock in concrete aggregate burned out my first hammer drill. Strange mix with underground lakes on the buried shelves. The engineering for foundations can be challenging.
ReplyDelete