Glacial landscape of the Himalayas

Creation of glacial landscape:

            The Himalayas were formed through convergent processes. During the collision of the Eurasian and Indian plates, the large mountain range was formed over millions of years. The Himalayas are among the youngest mountain ranges on the planet and are growing at approximately 5 mm per year.

            Glacial ice is formed due to the compaction of snow and ice over time; where accumulation exceeds ablation. Alpine glaciers surrounding the Mount Everest region of the Himalayas are all currently in a state of retreat. The Rongbuck glacier, draining the north side of Mount Everest into Tibet, has been retreating 20 meters per year.

The Himalayas in 1,000 years from now:

An earthquake is likely to occur in the Himalayas near the border of Nepal in 1,000 years from now. Being that the mountains are atop the Eurasian and Indian tectonic plates, the convergence of the continental plates will likely cause a sudden release of energy. The plates shift several millimeters each year. These yearly shifts cause an estimated 140 earthquakes annually. Not only are earthquakes going to occur, the Himalayan Mountains will continue to rise as well. In China, the current elevation of the Himalayan Mountains is between 4,000-45,900 meters and is estimated to be growing 5 millimeters annually. In 1,000 years from now, the Himalayas will have grown roughly 5 meters, increasing the elevation to 4,005-45,905 meters.

Glacial landscape of the Himalayas in 10,000 years:

Earth has been in an ice age for the last 2.5 millions years. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating in 40,000 and 100,000-year intervals.  Earth is currently in an interglacial period and had its last glacial period was roughly 10,000 years ago. Arguably, Earth will likely experience a period of glaciation in another 30,000 – 100,000 years. Until then, Earth will probably remain in its interglacial period with warmer temperatures and receding glaciers. It’s likely that the Rongbuk glacier will retreat roughly 200,000 meters in 10,000 years.

Rongbuck glacier in 1921: Notice the downward movement of the glacier due to the slope. Notice also the formation of a lateral (or medial) moraine. There also looks to be one cirque in this photo. (Retrieved from: http://www.glacierworks.org/glacier/main-rongbuk-glacier/)

Rongbuck glacier in 2007: Notice the glacier has retreated. There also looks to be a knife-like ridge, or an arête, on the right. The cupping of the snow is due to sublimation. (Retrieved from: http://www.glacierworks.org/glacier/main-rongbuk-glacier/)

The Himalayas in 1,000,000 years:

In 1 million years, assuming Earth is still in an ice age since glacial ages come about every 250 million years, the face of the Himalayas will look quite different from today. Glaciers will advance and retreat about 10 times (100,000 x 10) and will be retreating in 1,000,000 years. As glaciers retreat, they leave behind till and other depositional landforms. There will likely be more extensive lateral moraines, which are mounds of till that collect on valley sides due to rock falls and plucking of valley walls. Glacial lakes may form, since near the end of the last glacial period about 10,000 years ago, the retreating glaciers often left behind large deposits of ice, melting and creating tarns. Flora and fauna will likely advance further into U-shaped valleys as well.

Notice the medial moraine development in the lower photo. Notice also the tarn in the upper photo. The comparison of both photos shows Rongbuk glacier in a state of retreat.

(Retrieved from: http://www.markhorrell.com/blog/wp-content/uploads/comparison_2009.jpg)

Conclusion:

Overall, the Himalayas will likely change over the next thousand, ten thousand and one million years in the future. Different processes, such as plate convergence, will create earthquakes and new mountains. Depositional, as well as erotional, landforms will be created due to receding glaciers, changing the face of the Himalayan landscape.

References:

http://www.ux1.eiu.edu/~cfjps/1300/glaciers.html

http://www.pbs.org/wgbh/nova/everest/earth/glacier2.html

http://www.100gogo.com/hima.htm

http://khabarsouthasia.com/en_GB/articles/apwi/articles/features/2012/11/28/feature-02

http://www.eduweb.com/portfolio/bridgetoclassroom/platescollide.html

http://www.learner.org/interactives/dynamicearth/slip2.html

Trade winds, Jet Streams and Monsoons

            China is located at 32.9043° N, 110.4677° E, whose general latitude ranges between roughly 20° N - 50° N. The large land mass is thus affected by different wind circulation paths. Trade winds are winds that blow east to west, while winds that flow from west to east are known as jet streams. Jet streams fast-moving high-altitude narrow air currents in the atmosphere. Tropical easterly winds affected by the subtropical jet stream move from east to west toward the ITCZ while westerly winds move to the east toward the subpolar jet stream. China is mainly influenced by the high, subtropical jet stream. Northern jet streams are caused by a combination of the planet’s rotation as well as atmospheric heating, where boundaries of meandering air masses hold differences in temperature. Jet streams move moisture in Earth’s atmosphere and are partially responsible for changes in our weather. 

The photo on the left depicts Earth's trade winds and the corresponding jet streams. Notice direction of the winds as well as the latitudes of the jet streams. The photo on the right depicts the flow of Earth's jet streams, which travel west to east. Right:http://ww2010.atmos.uiuc.edu/guides/mtr/hurr/gifs/mvmt1.gif

Left: http://whyfiles.org/wp-content/uploads/2010/10/jet_stream_globe.jpg

As hot air rises, due to the sun warming the Earth’s surface, water vapor also rises into the sky near the equator. As the Northern hemisphere warms in spring and summer, the winds change due to a differences in pressure, in part caused by warm and cold fronts. Monsoon winds, for example, blow in opposite directions during different times of the year and are accompanied by corresponding changes in perception. Monsoons in China occur in this way. Instead of the winds blowing towards Africa via the tropical easterlies, the wind blows across the Indian Ocean all the way to Japan. China’s summer monsoon includes warm winds from the tropics and picks up large amounts of water due to evaporation as it crosses the India Ocean. As the warm, moist winds lift and travel over the Himalayas and the Tibetan Plateau, it condenses into rain or snow.

This diagram depicts China's summer monsoon winds. Winds pick up large amounts of water from the Indian Ocean and travel towards Japan, changing direction in the fall when the temperatures begin to drop.

Image: http://www.shrimpnews.com/Graphics/ShrimpPictures/Monsoon.JPEG

Info source: http://www.yourchildlearns.com/china-monsoon.html

Debris Flow in Zhenhe

On Thursday, October 4, 2012, a hillside in Zhenhe collapsed, burying Tiantou Elementary School and 18 students in a landslide. Sources refer to the event as a landslide, but according to our notes, a landslide simply describes all rapid forms of mass wasting. When examining the media, the event sounds and looks to be categorized as a debris flow. Debris flows have high viscosities and contain a lot of mud as well as rock debris, unlike mudflows that have less debris with some rock content. Being that the hillside collapsed, gravity and a steep slope clearly influenced the debris flow to occur.

Prior to the debris flow, there was seismic activity as well as a large amount of rain flow. On September 8^th, a series of tremors hit the region, killing dozens of individuals. Other earthquakes throughout September left the land prone to mishaps, and in addition to the sizeable amount of rain, mass wasting occurred and created a debris flow. The debris flow is estimated to have killed 19 people, 18 of which are children. The landslide also affected people in the area by burying three houses and damming a nearby river. The river’s water pooled around the buried area to approximately 45 feet across and 21 feet deep. The pooled area hindered rescue efforts and forced some 800 people from their homes in Yiliang County.

BBC video of the debris flow:

BBC NEWS. 5 October 2012. Retrieved from: http://www.bbc.co.uk/news/world-asia-china-19839932

Examiner. 7 October 2012. Retrieved from: http://www.examiner.com/article/chinese-landslide-results-deaths-of-18-students

Formation of Mount Everest

            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

Introduction

This is a joint blog created by Marissa Jones and Kelly Victor for the fall semester of 2012. We are both undergraduates taking Physical Geography at the University of Colorado at Denver.

 Mt. Everest

For this blog, we have selected China as our country of geographical study. We have chosen China because there is a wide range of landscape to investigate within its five divisions. From snow-capped mountains to sandy dunes, China possesses an abundant amount of physical geography to be studied. We'd also like to travel to China some day to experience its culture and explore its varying physical landscapes for ourselves.

Ming Sha Sand Dunes

Photo credits:

http://www.cs.sfsu.edu/~huiyang/photo_china.htm

http://mslinder.wikispaces.com/Sublimeproject