Rocks and Geology

cool

Local basalt (I think) used in an art work.




Much of the underlying geology here is Devonian. There are a fair amount of significant fish fossils being unearthed up in the mountains.

Extreme heat and pressure caused the folding. Sedimentation likely caused the layering affect. Yes, the verticle chanels are from blast holes. Looks like a couple of intrusions too (where one type of rock seems to seep through a different type). I'll wait for Fman for more details.

Great idea Rosborn. I hike regularly in the Fells here in MA. There's some good geology, including volcanic rocks and glacial striations.

Dadpad, that looks like sandstone to me..... but, what do I know.

Its as hard as hell littlek. If it is sandstone it unlike any i've ever seen.

I guess not, then!

basalt is usually black, if that layering (shown vertically) isnt sedimentary, Ill eat a bug.

My project is now involving writing an intro geology text using the Appalachians to explain how geologic analyses are done.

Hey fman, nice project!

I could live with sedimentary. Theres a fair amount of mudstone here. I'm fairly sure the different coloured layers are a result of the artists routing. The outside laye of the rock has weathered to produce the rusty look.

Off topic i know but the home containing the exhibition those rocks were part of is a rammed earth structure you can see a little in the background.
I've got some photos somewhere but my datastream has been shaped to dial up speeds so it might be a while before i can get at the photos.

I'm always amazed at the lenghts Our Lord goes to just to make it look like the earth is more than a few thousand years old.

Mudstone


Although it seems solid when first unearthed



It quickly breaks up when exposed to the elements and crumbles to pebbles



There used to be a slate mine up in the hills here run by the Devonian Slate company. The slate was apparently not the best quality and italian imports put em out of business.
Its real deliverence country though and a good drive away so no photos

Thread about rammed earth houses
http://able2know.org/topic/143519-1

Cool beans, Roswell . . . thanks for the thread . . .

Would the rocks in that photo be considered metamorphic?

yes, and they are on the edge of remelting into a more granitic type rock. That phenom is called anatexis and is , technically, a fourth class of rock.
New ENgland is a funky area geologically. Its been the leading edge of continental collisions at least 3 times so , not only do we see metamorphosed sedimentary rocks and igneous rocks, we see re melted and re metemorphosed rocks. These can be seen in microscopic sections and in "reset" isotope clocks in the minerals of the rocks.
We look for zircon minerals and analyze their components for the isotopic clock data. Beyond that, the standard tool is a surveying compass with which we can map the trends of rock cleavage and cracks and these "fold" axis in metamorphic rocks. These map trends are also a working tool to analyze deformation sequences. Youll see geologic maps with what look like weather forecast symbols and tiny "capital T's". These are shorthand symbols used by geologists to tell map readers that the trends of deformation has been studied in a specific area.
I use them a lot to search for specific mineral types.

In MAine, in the early 1840's (just before the CAlifronia gold strike) there were several gold strikes in New Brunswick , Maine, Connecticut, and Pennsylvania. In fact, gold is found in commercial deposits all the way down the Eastern flanks of the Appalachians. The largest US deposits of gold (after Alaska) are found in South Carolina and before that, Pennsylvania in the iron deposits of Cornwall and the Grace deposits. (My specialty is finding little hunks of **** in giant masses of crystalline rocks.So Im always on the lookout for large crystalline deposits of rocks with which to assess theior mineral content. Hence, metamorphic rocks are a big area of interest to me.

The USGS has a good map of New England. You go to USGS.gov and go to theior store and you will find all kinds of classic maps for anywhere in the US. New England and Canadas maritimes was where most of the original interpretation of global tectonics was accomplished. So the maps are abundant.


PS, anythime you can actually see linear trends of minerals within a rock outcrop, thats usually a sign pf a metamorphic or anatexctic sdeposit. Igneous rocks are usually always non lineation filled (except in large regional senses where you need an airphoto to detect contacts of different minerals). Linear elements can be seen in sedimentary rocks also , but these lineations are called "bedding" or layers (like a cake).

That's the best map I could find of the area, but it doesn't have enough detail with roads and town names to figure out exactly what age of rocks I was looking at.

My photo was taken in Milford NH.

QAlmost every state's survey (except RI and DSel) publishes a "tourist: geology map of the state. That also means that there is a full geo map with towns roads and counties. There is also a series of guidebooks published by Mountain Press of Missoula Montana. These are the "Roadside Geology of ( enter states name here)". Theres one called "The Roadside Geology of Vermont and New Hampshire". These are mostly field guides to interesting geology features and photo-ops. Ill PM you their website so Im not messin with policy .