A Turtle's Back Rock Formation
Posted by: Groundspeak Premium Member Lord Elwood
N 40° 46.220 W 074° 16.485
18T E 561206 N 4513515
Quick Description: The Turtle Back Rock ares is nestled within the 2,000 acres of the South Mountain Reservation, South Orange, NJ. Park off Walker Rd, Follow the orange/white to the rock formations.
Location: New Jersey, United States
Date Posted: 10/8/2007 4:34:42 AM
Waymark Code: WM2BPK
Published By: Groundspeak Premium Member RakeInTheCache
Views: 184

Long Description:
The Turtle Back Rock area was named after a rock formation which resembles the back of a turtle shell. All of the boulders and rocks in this area have the same hexagonal lines and markings etched into the surface.

Basalt lava once flowed through the Newark rift Basin valley. When the basaltic trap rock cooled, it fractured into small hexagonal blocks. Minerals filled in the cracks and voids before it was covered again. Natural erosion wore away the basalt faster than the minerals. The result was a rock pattern similar to a turtles shell.

An article can be found in Weird NJ magazine, Vol. 11 page 48. Please watch you step around the cliffs and rock formations.

Brief explanation: Basalt is the usually hard and black volcanic rock formed from (liquid) basaltic lava. Basaltic lava contains less than about 52 percent silica (SiO2) by weight. Because of its low silica content, it has a low viscosity (resistance to flow). Therefore, basaltic lava can quickly and easily flow more than 20 km from a vent. The low viscosity typically allows volcanic gases to escape without generating enormous eruption columns, although basaltic lava fountains and fissure eruptions, however, still can be hundreds of meters tall. Basaltic lava is erupted at temperatures between 1100 to 1250°C. Basalt is by far the most common volcanic rock type. Basaltic magma is formed by partial melting of material from the upper mantle, and and is therefore typical for volcanism at hot-spots and at rift-zones. In these areas, upwelling of the mantle (either caused by a rising mantle plume underneath hot-spots, or by a divergent plate boundary at mid-ocean rift zones) decreases the pressure of the hot rock and therefore causes (partial) melting. Oceanic crust and submarine volcanoes consist largely of basalt, because most of them are formed at rift-zones (all ocean floor) or hot-spots. Among subaerial volcanoes, basaltic lava is primarily found at shield volcanoes. Basaltic lava flows can be subdivided into two end-member structural types, according to their flow surfaces:-- Pahoehoe lava - smooth, billowy, or ropy surface.-- A'a' lava - fragmented, rough, sometimes spiny, or blocky surface... The Newark rift basin contains Triassic and Jurassic rocks deposited in a large sedimentary basin that formed during the breakup of Pangea. The giant continent that existed about 250 to 200 million years ago. The Newark basin forms the largest physiographic province (Piedmont province) in the northern half of New Jersey. Because the Newark basin makes up more that 95% of the Piedmont province, most geologists simply refer to this area as the Newark basin. The rocks within the Newark basin consist predominantly of siltstone and shale, along with sandstone and conglomerate. Most of these rocks have a reddish color, which gives the soils in the Newark basin a reddish hue. The Newark basin also contains lava flows and intrusions, the largest and best known of which is the Palisades sill. [A fault is a break or fracture in the Earth's crust along which movement takes place.]

Nature has a way in manifesting and representing itself in many ways. The same shapes and lines appear in all living and non living parts in Nature and this great Earth.
Waymark is confirmed to be publicly accessible: yes

Access fee (In local currency): .00

Requires a high clearance vehicle to visit.: no

Requires 4x4 vehicle to visit.: no

Public Transport available: no

Website reference: [Web Link]

Parking Coordinates: Not Listed

Visit Instructions:
No specific requirements, just have fun visiting the waymark.
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Recent Visits/Logs:
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BigA800 visited A Turtle's Back Rock Formation 2/15/2009 BigA800 visited it
RMR45 visited A Turtle's Back Rock Formation 6/10/2008 RMR45 visited it
Lord Elwood visited A Turtle's Back Rock Formation 10/8/2007 Lord Elwood visited it
Math Teacher visited A Turtle's Back Rock Formation 4/24/2007 Math Teacher visited it

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