Delhi Ridge Earthcache EarthCache
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Access to the cache must be from Sardar Patel Marg. You cannot reach the cache from Buddah Jayanti Park.
The Aravalli (line of peaks) Range, runs approximately 800 kms from the Indian state of Haryana near Delhi southwest through Rajasthan and ending at Palanpur near Ahmedabad, Gujarat. Guru Shikhar is the highest peak at 5653 feet (1723 meters)..
The Aravalli Range was formed 1.5 billion years ago when the movement of tectonic plates caused an upward thrust of the Earth’s crust, forming “folded mountains”. Mountains that are continuing to rise, such as the nearby Himalayas, which are a relatively young 50 million years old, are called “young fold mountains”. Ranges where the movement has stopped, such as the Aravalli, are called, “old fold mountains.” Millions of years ago the Aravallis were extremely high but over time have worn down almost completely by weathering.
The Delhi Ridge is a 35 kilometer extension of the Aravalli Range along the northern and western edge of Delhi from Tughlaqabad, near the Bhatti mines, tapering off near Wazirabad on the west bank of the Yamuna river. The ridge is made up of primarily quartzite rocks. It serves as the green lungs of the city and almost 170 hectares were declared a Reserved Forest in 1915. Development and the encroaching city have halved this area to less than 87 hectares today. It is important to the residents of Delhi as its elevation and vegetation protects the city from the hot winds of the Aeolian deserts of Rajasthan to the west.
The Delhi Ridge was once mined for its forests, minerals, mica, sand, stone, rocks and water. The dense forested land was turned into pits and hillocks. The site of the earthcache will take you to one of these pits where evidence of the mining can easily be seen.
Scientists from the Centre for Environmental Management of Degraded Ecosystems at the University of Delhi are trying to return the area to its natural state by removing invasive weeds and replacing them with native trees and bushes. So far the scientists have reintroduced over 10 ecosystems with over 40 biotic communities. A rangeland with native grasses and a Conservatory of Butterflies, orchidarium and fernary have been developed.
Two types of rock commonly found in the Ridge are Granite and Sandstone.
Granite is a common type of igneous rock that can contain quartz and feldspar and possibly mica. Igneous rocks are formed when the magma, or molten rock deep under the surface of the Earth, is forced to the surface by the moving of plates or the buildup of pressure from the heat. As the magma gets closer to the surface, it cools, creating igneous rocks. Granite is extremely durable and hard, making it the perfect substance for construction uses in such items as countertops or flooring.
Sandstone is a sedimentary rock composed mainly of sand-sized grains of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Sandstone is formed when layers of sand accumulate (called sedimentation) either as the grains settle from being suspended in water, or cease to be blown across the land such as from a sandy desert. Once it accumulates, the sand is compacted by pressure from overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains. Sand grains range from 0.0625 mm to 2 mm (0.002–0.079 inches). Some sandstones are resistant to weathering, yet are easy to work, making them a common building and paving material.
The listed coordinates take you to a spot overlooking a quarry that is about 100 years old. Supposedly the granite from this area was used for the foundation of the Viceroy’s House. The foundation was laid in 1912 but it took 19 years to complete when World Ware One interrupted construction. It served as the official residence of the Viceroy of India until independence when it became the official residence of the President of India and renamed the Rashtrapati Bhavan. With a floor plan of 19,000m2 and total space of 241,000 m3, it is the largest residence of any Head of the State in the world.
Just a few meters from the listed coordinates is a large sandstone outcrop. Sandstone was also used in the construction of the upper parts of the Rashtrapati Bhavan, although it was mined from Rajasthan and not this site.
To claim credit for the cache please e-mail me the following information:
a) What type of rock are you standing on at the listed coordinates?
b) Looking across the quarry site, what type of rock forms the wall in front of you?
c) Do you think the sandstone in the area was formed from sedimentation from water or air, and explain your reasoning.
d) Is the grain size of the sandstone small (i.e. closer to 0.0625 mm) or large (i.e. closer to 2 mm)?
e) Take pieces of granite and sandstone. Rub them together. Is there a noticeable difference between the hardness of the rock? Which one seems harder than the other? How much effort does it take to rub away parts of the softer rock?
f) If granite and sandstone both contain some of the same materials, why is one harder than the other?
Although not a requirement to get credit for the find, please post a photo of yourself at the quarry.
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