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#17608 - 02/22/06 08:46 PM Re: Shawangunk radio essay text [Re: yorick]
Timbo Offline
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Registered: 12/23/99
Posts: 694
Loc: Delaware
Quote:


Here in Ulster County, there is a ridge that rises between its lush and lovely river basins, curling up to quartzite crags




Gol darnit, for the umpteenth time, it's not quartize it's a (quartz) conglomerate. There is a difference.

TS
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#17609 - 02/22/06 09:14 PM Re: Shawangunk radio essay text [Re: Timbo]
oenophore Online   confused
Carpal Tunnel

Registered: 09/24/01
Posts: 5962
Loc: 212 land
Quote:

Quote:


Here in Ulster County, there is a ridge that rises between its lush and lovely river basins, curling up to quartzite crags



Gol darnit, for the umpteenth time, it's not quartize it's a (quartz) conglomerate. There is a difference.
TS


I'm not a professional, yet I recall in my intro geology class that the visible difference between quartzite and sandstone is that the latter rock breaks around the sand grains, while if the former is broken, the grains will break too. In my Gunks observations, I've seen places where the rock breaks around the pebbles, even places where pebbles have fallen out. In other places, top of Arrow for instance, the pebbles are broken with the rock to present a smooth face. Whatever metamorphism had occurred seems to be non-uniform.
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#17610 - 02/22/06 09:50 PM Re: Shawangunk radio essay text [Re: oenophore]
yorick Offline
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Registered: 11/15/02
Posts: 1041
Loc: hamlet\'s hand
And I paid those geology fact checkers good money.

I wanted to use quartz conglomerate, or just conglomerate (but didn't think that would work for a general audience), and I kept pinching things to get it under three minutes, and lapsed into the shorter quartzite, yep, not thinking there's a difference. My proofers with some background in geology missed it, too. One of them says I can call it poetic license, but that don't sit right, given the piece's facts straightening point.

Thanks for the clarification, Timbo.



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#17611 - 02/22/06 10:13 PM Re: Shawangunk radio essay text [Re: yorick]
Timbo Offline
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Registered: 12/23/99
Posts: 694
Loc: Delaware
Quote:

One of them says I can call it poetic license, but that don't sit right, given the piece's facts straightening point.




Well, I gotta admit quartize flows off the tongue a lot better than either quartz conglomerate or conglomerate

T
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#17612 - 02/22/06 10:28 PM Re: Shawangunk radio essay text [Re: yorick]
Julie Offline
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Registered: 01/16/00
Posts: 2090
Loc: SoCal
Nice piece, Chris.

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#17613 - 02/23/06 03:00 PM Re: Shawangunk radio essay text [Re: Julie]
nerdom Offline
Pooh-Bah *

Registered: 09/07/01
Posts: 2483
Loc: Davis Sq., MA
Funny, I never heard anybody say, "I'm going climbing in the 'Gums' this weekend." Nice essay.
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#17614 - 03/01/06 05:11 PM Re: Shawangunk radio essay text [Re: oenophore]
Frank Florence Offline
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Registered: 01/05/00
Posts: 528
Loc: moved to Bend
Oenophore's description of quartzite conforms to that reported by the American Geological Institute.

Quartzite is listed twice in the AGI dictionary, once as a term for metamorphic rocks and once for sedimentary. In the latter case, the description is, "a very hard but unmetamorphosed sandstone, consisting chiefly of quartz grains that have been so completely and solidly cemented with secondary silica that the rock breaks across or through grains rather than around them; an orthoquartzite."

Notice that no thermal event or regional mountain building is implied. Silica solutions in the Gunks rock percolated through the strata and extensively filled voids. You can see this in the "whitey, tighty" layers that are especially recognizable at the top of the Arrow wall or out at Millbrook. The same solutions also are responsible for making the shale layers in the rock tough and brittle.

So Yorick had it right.


Edited by Frank Florence (03/01/06 05:12 PM)

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#17615 - 03/01/06 07:39 PM Re: Shawangunk radio essay text [Re: Frank Florence]
Timbo Offline
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Registered: 12/23/99
Posts: 694
Loc: Delaware
Quote:

Oenophore's description of quartzite conforms to that reported by the American Geological Institute.

Quartzite is listed twice in the AGI dictionary, once as a term for metamorphic rocks and once for sedimentary. In the latter case, the description is, "a very hard but unmetamorphosed sandstone, consisting chiefly of quartz grains that have been so completely and solidly cemented with secondary silica that the rock breaks across or through grains rather than around them; an orthoquartzite."

Notice that no thermal event or regional mountain building is implied. Silica solutions in the Gunks rock percolated through the strata and extensively filled voids. You can see this in the "whitey, tighty" layers that are especially recognizable at the top of the Arrow wall or out at Millbrook. The same solutions also are responsible for making the shale layers in the rock tough and brittle.

So Yorick had it right.




Yes, there is sedimentary and metamorphic quartzite, but the (climbable) Gunks rock is still neither.

The quartzite at Devil's Lake, Wisconsin is a great example of a sedimentary quartzite. The Tuscarora Sandstone (Seneca) is a great example of a metamorphic quartzite. The Gunks Conglomerate is neither. There is a large percentage of rounded quartz inclusions in the silica matrix. These inclusions are of a much larger size and derived from another source as the other material, thus it is a conglomerate.
TS
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#17616 - 03/01/06 08:34 PM Re: Shawangunk radio essay text [Re: Timbo]
oenophore Online   confused
Carpal Tunnel

Registered: 09/24/01
Posts: 5962
Loc: 212 land
There is a large percentage of rounded quartz inclusions in the silica matrix. These inclusions are of a much larger size and derived from another source as the other material, thus it is a conglomerate.

Is there no nomenclature for a conglomerate that breaks through the pebbles?
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#17617 - 03/01/06 09:34 PM Re: Shawangunk radio essay text [Re: oenophore]
Mike Rawdon Offline

Carpal Tunnel

Registered: 11/29/99
Posts: 4275
Loc: Poughkeepsie
I've always called Gunks stone quartzite conglomerate. Why can't it be both terms? There's conglomerate in a few spots in the Catskills; I might call that shaley conglomerate. If I thought I knew what it was, that is.

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