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EarthCache

NC Geology #1: Paleo Pavement Earthcache

Hidden : 7/6/2002
In North Carolina, United States
Difficulty:
1 out of 5
Terrain:
1 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

To do this cache you must be able to see color variations in the rock surface - that is the feature of interest.
Also please note that this property is owned by NC State Parks, and even though this an un-manned park, park operation hours are likely the same.
Please read the entire description and take a copy with you to the cache site - You'll need the info provided.



There is absolutely no bushwhacking necessary to find this location. The walk from the parking location to the feature is less than 0.10 miles, please take the path.
Please park on the grassy shoulder so that traffic can get by. The coordinates for the cache are for the park entrance off of Pulleytown Road. There is also parking off of Route 96, but if there is water, you may get wet or worse trying to get to the feature, rocks are moss covered and can be slippery.

Please note: This one is a virtual cache since the location you are finding is within a NC State Park and even thought this is an undeveloped/unmanned park I’ll respect the NC State Parks policy on no real-geocaches.
Also, it is NC State Park policy that you can not collect samples from or within the park boundaries.

To confirm this find you need to take a compass reading for the feature at the following coordinates N 35 55.085 W 078 23.392

Here is some info on the feature you are looking for.
The Setting: When you enter this park, you are approaching one of the largest naturally exposed outcrops of granite in NC. Such a large outcropping in a horizontal orientation is called a pavement, but please don’t try to drive on to it!

This is part of the Rolesville batholith - a batholith is a large mass of magma that cooled below the earth’s surface. Because layers of rock and earth above it insulated the magma, the mineral crystals are larger than if this had been a volcano and the magma had cooled on the earth’s surface.

Some of the rock that you are standing on cooled over 298 million years ago, during the Paleozoic Era. These rocks represent one of the youngest stages in the formation of the Alleghenian Mountain building event, which was a stage in the formation of the Appalachians mountains. The Rolesville batholith is the largest of these magma masses (otherwise called a pluton) in the southern Appalachians.

You are seeing only a fraction of it, N to S it runs from north of Henderson to south of Clayton - and that’s just where it is the surface bedrock!

The Feature: As the magma cooled, fractures formed, through which more magma rose through and then crystallized. Due to the chemical and physical nature of the rock (in this case granite) these fractures have specific characteristic orientation. The set of coordinates given in the description above is for a very large fracture which when you are standing on it you can see that it runs both behind and in front of you - take your reading looking in either direction.

Extra credit: If you find another fracture that intersects the feature or another set of intersecting fractures you could then measure the angle that is characteristic of fracturing in granite, and earn 10 extra credit points for Geology I. (Don’t happen to have protractor with you – take the compass reading for each and subtract and this will give you one of the two angles formed. The other angle is your first value subtracted from 180).

To log this find: Email cache owner the compass reading and extra credit info for confirmation, do not include it in your log, not even encrypted. When you see the feature, you will understand what I mean by taking a compass reading.


By the way, the majority of the outcrop is a Monzonite, medium grained rock, with feldspar (White, matted mineral) predominant, some hornblende (Black mineral) and quartz (Gray, glassy mineral). By comparing the crystal size in the feature with the surrounding rock, you can see what a good insulator granite can be – the bigger the crystals, the slowed the cooling. Granite with such large crystals is called a Pegmatite.

Note: Geologic information compiled from Field Trip Guidebook, 50th Annual Meeting Southeastern Section Geological Society of America, Raleigh, NC, April, 2001

Additional Hints (Decrypt)

Gur srngher lbhe ner ybpngvat vf n irel ynetr senpgher gung ehaf orgjrra gjb Ynetr ryvcgvpny cbbyf, xabja nf cbgubyrf. Gur fbhgurea cbgubyr vf whfg va sebag bs n ybt wnz/envfr nern naq vf nobhg 1.5 srrg qrrc. (Cbgubyrf ner gur erfhyg bs rebfvba nf gur Yvggyr Evire ehaf bire guvf bhgpebc, ohg gung’f nabgure trbybtvpny fgbel.)

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

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Inventory

There are no Trackables in this cache.

 

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245 Logged Visits

Found it 238     Write note 6     Post Reviewer Note 1     

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Current Time:
Last Updated: on 6/29/2014 10:43:31 AM Pacific Daylight Time (5:43 PM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum