Mount
Everest formed along the border of China and Nepal approximately 60 million years ago at the Indian and
Eurasian plates. As the Indian plate moved north, it gradually closed what was
once known as the Tethys Ocean, which had separated fragments of Pangea.
Mafic
rock tends to dominate the ocean crust, while felsic rock tends to dominate
continental crusts. Felsic rock tends to be light in color and obtains a
silicon base. Quartz, which contains silicon and oxygen, is rich in silicate
and is often found in sedimentary rocks. The quartz-rich felsic rock that
existed along the Eurasian plate was not dense enough to subduct into the
Earth’s mantle, while the heavy ocean floor north of India submerged into the
mantle, dragging India along with it. Thus, the Tethys seabed converged into a
high mountain range known as the Himalayas. Today, Mount Everest stands at 29,029 feet above sea level.
At
the summit of Mount Everest are fossils and limestone, which were formed by
biologic activity. Sediment produced by biologic activity is known as biologic
rock, while clastic rocks are formed from broken fragments of pre-existing
rocks. Thus, Mount Everest is an example of biologic and clastic sedimentary
rocks. The mountain is a great accumulation of sedimentary rock, which has
lithified to form strata.
Deep-water
marine shale as well as gneiss, slate, and sandstone are all found on Mount
Everest as well. Shale is a clastic sedimentary rock mainly composed of small
fragments of clay and quartz, while sandstone – also a clastic sedimentary rock
– is composed of sand-sized minerals. Gneiss, a metamorphic rock, displays
compositional banding, or foliation, of pre-existing igneous and/or sedimentary
rocks. Slate is also a metamorphic rock composed of shale, which, as mentioned
above is mainly composed of clay or volcanic ash.
Bilham, Roger. (2000). Birth of
the Himalaya. NOVA, PBS Online. Retrieved from: http://www.pbs.org/wgbh/nova/everest/earth/birth.html
Igneous Metamorphic Sedimentary
Rock Gallery. Rocskandminerals4u. Retrieved from: http://www.rocksandminerals4u.com/igneous_metamorphic_sedimentary_rock.html
