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| Sunday, 31 July 2005 |
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Junior Observer |  |
| News Business Features Editorial
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Mountain of pink quartz
The pink quartz mountain range has a history of more than 550 million years and belongs to the prehistoric era. Archaeologists are of the view that this is the largest pink quartz mountain range in South Asia. The mineral in the rock is identified as quartz, as it's mainly made up of silicon dioxide (SIO2). In the middle of the earth, there are hot gases, and liquids and rocks explode out of the ground as magma lava. When this magma lava flows out, sometimes, portions of the liquid are retained in the internal spaces. These are formed into quartz. Quartz is a mixture of magma, lava and silicon dioxide and its cells are rectangular. The pink colour of the quartz has come from a chemical mixture of silicon and titanium. Due to the various types of mineral deposits, part of the soil is not suitable for the growth of plant life. Initial beliefs are that the fossils in the soil bed could date as far back as over 20 million years. It has been reported that the Indian Moghul King Shah Jehan used pink quartz from this mountain range to build the windows of the Taj Mahal, in memory of his beloved wife Mumtaz. Namal Uyana is said to have been used as a monastery during the reign of King Devanampiyatissa. By the eighth century, during the reign of King Dapulu IV, it had been turned into a sanctuary, where people could flee from persecution and remain free, as long as they stayed within its confines. Several stone inscriptions giving details of the existence of the Namal Uyana and the sanctuary have been found in the Anuradhapura area. These also appear in one of the only two octagonal stone inscriptions found in the country so far. ############ Sedimentary rocks
When mountains are first formed, they are tall and jagged like the Rocky Mountains on the west coast of North America. Over time (millions of years), they become old mountains like the Appalachian Mountains on the east coast of the United States. When they are old, they are rounded and much lower. What happens here is that lots of rock gets worn away due to erosion. Rain, the freeze and thaw cycle, wind and running water cause the big mountains to crumble a little bit at a time. Eventually, most of the broken bits of the rock end up in the streams and rivers that flow down from the mountains. These little bits of rock and sand are called sediments. When the water slows down, these sediments settle to the bottom of the lake or oceans they run into. Over many years, layers of different rock bits settle at the bottom of lakes and oceans. Gradually, the layers of sand and mud at the bottom of lakes and oceans turn into rocks. These are called sedimentary rocks. Some examples of sedimentary rocks are sandstone and shale. Sedimentary rocks have fossils in them because plants and animals that have died get covered up by new layers of sediment and are turned into stone. Most of the fossils we find are of plants and animals that lived in the sea. They just settled to the bottom. Other plants and animals died in swamps, marshes or on the edge of lakes and were covered with sediments when the lakes got bigger(expanded). When large amounts of plants are deposited in sedimentary rocks, they turn into carbon, which gives us coal, oil, natural gas and petroleum. Sedimentary rocks cover 75 per cent of the Earth's surface. Most rocks found on the Earth's surface are sedimentary even though sedimentary rocks make up less than five per cent of all the rocks that make up the Earth.There are six main types of sedimentary rocks, depending on their appearance. Conglomerate rock has rounded rocks (pebbles, boulders) cemented together in a matrix. Sandstone is a soft stone that is made when sand grains cement together. Sometimes the sandstone is deposited in layers of different coloured sand. Shale is clay that has been hardened and turned into rock. It often breaks apart in large flat sections. Limestone contains many fossils and is made of calcium carbonate and/or
microscopic shells. Gypsum, common salt or Epsom salt is found where sea
water precipitates the salt as the water evaporates. Porphyry rock forms
when jagged bits of rock are cemented together in a mass. |
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Namal Uyana at Ulpothagama in the Anuradhapura district is famous for
its pink quartz mountain and could be the home of one of the world's
largest beds of fossilized plants. 
In a recent issue, we told you about rocks and the different types of
rocks. This week we tell you more about sedimentary rocks .