Tripod Rock is glacial erratic located in Pyramid Mountain
Natural Historical Area, Kinnelon, New Jersey. There are more than
1300 acres of rugged trails, fields, forests, rock outcroppings and
wetlands, providing a wide range of geological and ecological
experience. This wilderness land was used as a hunting, fishing,
and gathering site or over 10,000 years by Native Americans,
including the Lenape Indians, who were encountered by the first
European settlers over three hundreds years ago. Many of these
first explorers, traders, and settlers who discovered this special
corner of old Pequannock were of Dutch extraction. Surveyor's
stones and enduring stone walls still mark the homestead farms and
woodlot boundaries.
There are many tripod rocks in the USA but this is believed to
be the largest. This famous multi-ton boulder does line up along
magnetically lines, and the summer solstice sets thru a small notch
in the rock. Coincidence? The site held a spiritual significance
for the local Indians, and even today for the spiritually inclined.
Tripod Rock is estimated at 15 feet long, 12 feet wide, and 8 feet
high and is balanced on three smaller boulders. It There is a
peculiar triangular crest running the length of its top. The entire
boulder is balanced two feet above the bedrock on three smaller
stones. The point of contact between the main boulder and its
support stones formed an approximate 3-4-5 triangle.
The accepted Geologists theory is that the Wisconsin glacier
dropped this boulder from not too far away and is probably made
from quartzite, Kittatinny Mountain's bedrock. Over the last 18,000
years or so, smaller rock and sand particles that were underneath
it eroded away, leaving the boulder and its legs smaller slabs of
rock that it came to rest on. Someone has inserted other types of
rock under the boulder, to replace the smaller support rock that
now crumbles and erodes.
Geologist for the New Jersey Geological Survey, says the rock is
made of gneiss and so is the ledge it's sitting on. "It probably
didn't come from very far because the glacial erratic's in this
part of the country only come from about 10 to 20 miles away." They
tend to be on rock ledges or ridge tops that have not eroded away.
"In many respects they are not super uncommon but it's not that
unexpected or unusual. All they need to be produced is when you
have a great number of boulders and cobbles, and when they hit
something solid like that outcrop, there's a good chance for
them."
About 30 feet away from Tripod Rock stands a boulder arrangement
triad of Tripods which appears to form a triangle. These smaller
ones are about 4-7 feet wide, two large boulders balanced partially
on two smaller stones for the base. The apex is about 15 feet away
and in the form of a smaller rock. The apex of the triangular
configuration points to a hill forming the horizon. Intriguingly,
it has been observed that this sight line forms the setting point
of the sun on the summer solstice. Some people may wonder about the
odds of three Tripods in one location. Is it a monument to the
power of sheer chance and geological forces? Or did someone build
the tripods?
Naturalist for Pyramid Mountain, says that although park
personnel believe that Tripod Rock is glacial, their opinion about
the two smaller ones ("Solstice Stones") is ambiguous. "We believe
the Solstice Stones were placed there (by Native Americans) because
it was probably a ceremonial site. The sun sets between those two
rocks." The Solstice Stones each sit on three small rocks, forming
small tripod rocks, just like the big one nearby. Para says you can
sit on a certain cleft rock behind the two Solstice Stones and
watch the sun set between them on the summer solstice. The fourth
tripod-in-the-making has one or two stones under it and appears to
be waiting for a third to officially make it a tripod rock.
Tripod Rock begetter of mystery, artifact of glacial motion or
signpost of American Indians on a Morris County mountaintop? Tripod
Rocks is not to be missed and a phenomena for all to enjoy.
EARTHCACHE.ORG GUIDELINES FOR LOGGING AN EARTHCACHE:
EarthCache sites must provide Earth science lessons. They take
people to sites that can help explain the formation of landscapes
or to sites of interesting phenomena such as folds, faults,
intrusions or reveal how scientists understand our Earth (such as
fossil sites etc.) EarthCache sites must be educational. They
provide accurate but simple explanations of what visitors will
experience at the site. Logging of an EarthCache must involve
visitors undertaking some educational task that relates to the
Earth science at the site. This could involve measuring or
estimating the size of some feature or aspect of the site,
collecting and recording data
TO LOG THIS EARTHCACHE YOU MUST COMPLETE THE FOLLOWING ( 2)
EARTH SCIENCE LESSONS ON PSI AND WEATHERING:
~ PSI ~ LESSON #1~
You must calculate the PSI or Pounds per Square Inch of pressure
on to which Tripod Rock is exerting on the three smaller supporting
rocks. You can calculate the PSI weight by measuring the amount of
total surface of the smaller three rocks which are in contact and
holding up the large boulder. Then you must calculate the weight of
Tripod Rock.
1) You need to measure the contact surface AREA of the
each of the three smaller rocks which are touching the underside of
Tripod Rock. This contact surface AREA can be found by looking
under Tripod rock and by examining the three small rocks. Measure
and multiply the length and width of each of the small three rock
contact point, then add the three totals of contact surface AREA
together to get the overall total AREA. Your answer should be in
total square inches.
2) You need to estimate the FORCE and measure the weight
of Tripod Rock. The average weight estimate of a granite boulder is
approximately 175 pounds per cubic foot. Granite is similar in
weight to glacial erratic's, use this weight for the calculations.
To estimate the quantity, you need to convert the area into cubic
feet by multiplying length x width x height of Tripod Rock. Please
post your estimated size of tripod Rock.
MEASUREMENT EXAMPLE ~ 27 CF X 175 LBS/CF = 4725 LBS:
3) To find the amount of PSI or Pounds per Square Inch of
pressure on to which Tripod Rock is placing on the three smaller
rocks, divide the FORCE (weight) by the AREA (Total Sq.inches) on
which you apply force. Use the following formula: Force (F) / Area
(A) = Total PSI ~ Pressure (P)
4) YOU MUST EMAIL ME YOUR PSI LESSON #1 ANSWER, PLEASE DO NOT
POST YOUR ANSWER IN YOUR LOG. PLEASE POST ONLY YOUR WEATHERING
LESSON #2 EXAMPLES OUTLINED BELOW IN YOUR LOG.
~ WEATHERING ~ LESSON #2
Weathering is the breaking down of Earth's rocks, soils and
minerals through direct contact with the planet's atmosphere. Rocks
are symbols of strength and durability. Although some types of rock
are in fact strong and resistant to weathering, other types break
down rather easily over time. Acid rain can make short work of a
rock's structure, and even regular rainwater will deteriorate rocks
over time. Rocks that weather more quickly than others have a
molecular structure and mineral content that makes them more
susceptible to erosion.
Two important classifications of weathering processes exist
— physical and chemical weathering. Mechanical or physical
weathering involves the breakdown of rocks and soils through direct
contact with atmospheric conditions, such as heat, water, ice and
pressure. The second classification, chemical weathering, involves
the direct effect of atmospheric chemicals or biologically produced
chemicals (also known as biological weathering) in the breakdown of
rocks, soils and minerals.
The materials left over after the rock breaks down combined with
organic material creates soil. The mineral content of the soil is
determined by the parent material, thus a soil derived from a
single rock type can often be deficient in one or more minerals for
good fertility, while a soil weathered from a mix of rock types (as
in glacial, aeolian or alluvial sediments) often makes more fertile
soil.
5) You must search the mountain top around Tripod Rock
and search for signs of "WEATHERING" among the varoius types of
rocks and boulders. Locate ONE example of weathering and describe
in detail what examples you located and is it physical or chemical
weathering . Please post your answer in your log. Examples
of different type of weathering can also be found at
http://en.wikipedia.org/wiki/Weathering.
6) YOU MUST TAKE A PHOTO OF YOU AND OR YOUR GPS AT TRIPOD
ROCK AND POST IT WITH YOUR LOG, LOGS WITHOUT PHOTO'S AND LOG
REQUIREMENTS WILL BE DELETED.
ENJOY YOUR VISIT!
Note: Parking is available at the main Visitor Center of Boonton
Avenue. To reach Tripod Rock follow the blue trail to the white
trail, the hike is over 1 mile from the parking lot, with a 200+
ft. elevation change hike.
The NNJC is about promoting a quality caching experience in
Northern New Jersey. For information on The Northern New Jersey
Cachers group, NNJC.org you can click here: http://www.nnjc.org
