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Glaciers cover about 10 percent of the land surface near Earth’s poles, and they are also found in high mountains. During the Ice Ages, glaciers covered as much as 30 percent of Earth. Around 600 to 800 million years ago, geologists think that almost all of the Earth was covered in snow and ice, called the Snowball Theory. Scientists use the evidence of erosion and deposition left by glaciers to do a kind of detective work to figure out where the ice once was and where it came from.

Glaciers are solid ice that moves exceptionally slowly along the land surface. They erode and shape the underlying rocks. Glaciers also deposit sediments in characteristic landforms. The two types of glaciers are: continental and alpine. Continental glaciersare large ice sheets that cover relatively flat ground. These glaciers flow outward from where the most considerable amount of snow and ice accumulate. Alpine or valleyglaciers flow downhill through mountains along existing valleys.


Glaciers erode the underlying rock by abrasion and plucking. Glacial meltwater seeps into cracks of the underlying rock, the water freezes and pushes pieces of rock outward. The rock is then plucked out and carried away by the flowing ice of the moving glacier. With the weight of the ice over them, these rocks can scratch deeply into the underlying bedrock making long, parallel grooves in the bedrock, called glacial striations.

Mountain glaciers leave behind unique erosional features. When a glacier cuts through a ‘V’ shaped river valley, the glacier pucks rocks from the sides and bottom. This widens the valley and steepens the walls, making a ‘U’ shaped valley.

Smaller tributary glaciers, like tributary streams, flow into the main glacier in their own shallower ‘U’ shaped valleys. A hanging valley forms where the main glacier cuts off a tributary glacier and creates a cliff. Streams plunge over the cliff to create waterfalls. Up high on a mountain, where a glacier originates, rocks are pulled away from valley walls.


As glaciers flow, mechanical weathering loosens rock on the valley walls, which falls as debris on the glacier. Glaciers can carry rocks of any size, from giant boulders to silt. These rocks can be carried for many miles over many years and decades. These rocks that are different in type or origin from the surrounding bedrock are glacial erratics. Melting glaciers deposit all the big and small bits of rocky material they are carrying in a pile. These unsorted deposits of rock are called glacial till.

Glacial till is found in different types of deposits. Linear rock deposits are called moraines and are named by their location relative to the glacier. Geologists study moraines to figure out how far glaciers extended and how long it took them to melt away. Lateral moraines form at the edges of the glacier as material drops onto the glacier from erosion of the valley walls. Medial moraines form where the lateral moraines of two tributary glaciers join together in the middle of a more massive glacier. Sediment from underneath the glacier becomes a ground moraine after the glacier melts. Ground moraine contributes to the fertile transported soils in many regions.

Terminal moraines are long ridges of till left at the furthest point the glacier reached. End moraines are deposited where the glacier stopped for a long enough period to create a rocky ridge as it retreated. Two end moraines form long Island in New York.

The ice of a piedmont glacier spills from a steep valley onto a relatively flat plain, where it spreads out unconstrained like pancake batter. Image by NASA Earth Observatory.

While glaciers dump unsorted sediments, glacial meltwater can sort and re-transport the sediments. As water moves through unsorted glacial till, it leaves behind the larger particles and takes away the smaller bits of sand and silt.

Several types of stratified deposits form in glacial regions, but are not formed directly by the ice. Varves form where lakes are covered by ice in the winter. Dark, fine-grained clays sink to the bottom in winter but melting ice in spring brings running water that deposits lighter colored sands. Each alternating dark/light layer represents one year of deposits. If during a year, a glacier accumulates more ice than melts away, the glacier advances downhill. If a glacier melts more than it accumulates over a year, it is retreating.

There has been a lot of conversations and research in the scientific community about the dramatic amount of glacial melt that has been occurring around the planet as of late. Glaciers flow incredibly slowly downslope under the influence of gravity. However, satellite imagery and on the ground data have shown that these glaciers are melting back and receding at an incredible rate. Because glaciers take so long to form and flow, they are excellent indicators of the temperature of the planet. As the planet has continued to warm over the last 100 years, glaciers from all around the world are retreating. This is important to humanity because glaciers make up a large portion of the usable fresh water on the planet. As these glaciers melt away, so do vast amounts of fresh drinking water, just at a time when the human population continues to grow at an exponential rate.


Agriculture, U. S. D. of. (2018). Soil in hand for planting [Photo]. Retrieved from https://www.flickr.com/photos/usdagov/44291041565/

Arbol de Piedra. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/7/7c/Arbol_de_Piedra.jpg

Atlas Pro. (n.d.). How Do Caves Form? Retrieved from https://www.youtube.com/watch?v=EX0q5I3-HZI

bikram79. (n.d.). Planet Earth Caves. Retrieved from https://www.youtube.com/watch?v=8U2SvhDaEv0

Bryce Canyon National Park (U.S. National Park Service). (n.d.). Retrieved February 16, 2019, from https://www.nps.gov/brca/index.htm

CNN. (n.d.). Greenland is Melting. Retrieved from https://www.youtube.com/watch?time_continue=4&v=UKKYt6fWob8

CrashCourse. (n.d.). Nitrogen & Phosphorus Cycles: Always Recycle! Part 2 – Crash Course Ecology #9. Retrieved from https://www.youtube.com/watch?v=leHy-Y_8nRs

Death Valley Sand Dunes. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/d/d2/Death-valley-sand-dunes.jpg

dimitris.g. (2015). Sunday Morning – Skala Oropou, Greece [Photo]. Retrieved from https://www.flickr.com/photos/dimitrisgiakoumis/30850795041/

Erosion and Deposition | CK-12 Foundation. (n.d.). Retrieved February 16, 2019, from https://www.ck12.org/book/CK-12-Earth-Science-For-High-School/section/10.0/

Exposure Labs. (n.d.). “CHASING ICE” captures largest glacier calving ever filmed – OFFICIAL VIDEO. Retrieved from https://www.youtube.com/watch?time_continue=7&v=hC3VTgIPoGU

G310Luke. (2008). Goodell Creek Debris Avalanche. Retrieved from https://commons.wikimedia.org/wiki/File:Goodell_Creek_Debris_Avalanche.jpg

Galuzzi, L. (n.d.). Bryce Canyon. Retrieved February 16, 2019, from https://upload.wikimedia.org/wikipedia/commons/4/4d/USA_10654_Bryce_Canyon_Luca_Galuzzi_2007.jpg

Goblin Valley State Park. (n.d.). Retrieved February 16, 2019, from https://stateparks.utah.gov/parks/goblin-valley/

Harper, D. (2009). Terracettes below Morgan’s Hill. Retrieved from https://commons.wikimedia.org/wiki/File:Terracettes_below_Morgan%27s_Hill_-_geograph.org.uk_-_1345945.jpg

Hazards – Utah Geological Survey. (n.d.). Retrieved February 16, 2019, from https://geology.utah.gov/hazards/

Landslides & Rock Falls – Utah Geological Survey. (n.d.). Retrieved February 16, 2019, from https://geology.utah.gov/hazards/landslides-rockfalls/

Lena River. (2019). Retrieved from https://en.wikipedia.org/w/index.php?title=Lena_River&oldid=881009903

Malaspina Glacier, Alaska. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/5/57/Malaspina_Glacier%2C_Alaska_%2822800052331%29.jpg

Mass Wasting – Physical Geology. (n.d.). Retrieved February 16, 2019, from https://opentextbc.ca/geology/chapter/chapter-15-mass-wasting/

Morbihan Iile Berder Rankosol Granite. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/5/5b/2013-morbihan-ile-berder-rankosol-granite0109.jpg

MSNBC. (n.d.). Amazing Drone Video Of World’s Largest Cave | msnbc. Retrieved from https://www.youtube.com/watch?v=nzoLZoTqQa8

National Geographic. (n.d.-a). Climate 101: Glaciers | National Geographic. Retrieved from https://www.youtube.com/watch?v=WJgpDyP9ewQ

National Geographic. (n.d.-b). He’s Watching This Glacier Melt Before His Eyes | Short Film Showcase. Retrieved from https://www.youtube.com/watch?v=HjLXLmlEmsw

National Geographic. (n.d.-c). Landslides | National Geographic. Retrieved from https://www.youtube.com/watch?time_continue=41&v=mknStAMia0Q

Nitrogen Cycle. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/d/de/Nitrogen_Cycle.jpg

NOVA PBS Official. (n.d.). Greenland Melting (360°). Retrieved from https://www.youtube.com/watch?v=rFBBu6lxA6o

Rabich, D. (2014). Deutsch: Wegekreuz am Kettbach, Hausdülmen, Dülmen, Nordrhein-Westfalen, Deutschland. Retrieved from https://commons.wikimedia.org/wiki/File:Hausd%C3%BClmen,_Wegekreuz_am_Kettbach_–_2014_–_3036.jpg

Siloso Beach Sentosa Singapore. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/e/ee/Siloso_Beach_Sentosa_Singapore_%2836589881162%29.jpg

Soil Profile. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/9/95/Soil_profile.png

Storyful News. (n.d.). Amazing Footage of Debris Flow in Illgraben. Retrieved from https://www.youtube.com/watch?v=Fsh5E9m3PrM

Talus ConesIsfjorden. (n.d.). Retrieved February 16, 2019, from https://upload.wikimedia.org/wikipedia/commons/d/d5/TalusConesIsfjorden.jpg

Tanyaş, H., Allstadt, K. E., & van Westen, C. J. (2018). An updated method for estimating landslide-event magnitude: An updated method for estimating landslide-event magnitude. Earth Surface Processes and Landforms43(9), 1836–1847. https://doi.org/10.1002/esp.4359

The Telegraph. (n.d.). What Causes a Landslide? Retrieved from https://www.youtube.com/watch?time_continue=1&v=RCxvbosa4fU

Types of landslide profiles. (n.d.). Retrieved February 16, 2019, from https://pubs.usgs.gov/fs/2004/3072/images/Fig3grouping-2LG.jpg

US EPA. (n.d.). Retrieved February 16, 2019, from https://www.epa.gov/

USDA. (n.d.). Retrieved February 16, 2019, from https://www.usda.gov/

USGS.gov | Science for a changing world. (n.d.). Retrieved February 16, 2019, from https://www.usgs.gov/

Utah Geological Survey – Keeping Utah informed with geologic data. (n.d.). Retrieved February 16, 2019, from https://geology.utah.gov/

Wavecut Platform Southerndown. (n.d.). Retrieved from https://upload.wikimedia.org/wikipedia/commons/6/63/Wavecut_platform_southerndown_pano.jpg

Weathering and Formation of Soil | CK-12 Foundation. (n.d.). Retrieved February 16, 2019, from https://www.ck12.org/book/CK-12-Earth-Science-For-High-School/section/9.0/

Weathering and Soil – Physical Geology. (n.d.). Retrieved February 16, 2019, from https://opentextbc.ca/geology/chapter/chapter-5-weathering-and-soil/

Weathering, Erosion, and Sedimentary Rocks – An Introduction to Geology. (n.d.). Retrieved February 16, 2019, from http://opengeology.org/textbook/5-weathering-erosion-and-sedimentary-rocks/

Wien, S. D. (2007). Deutsch: Steinschlag an der „Jalalabad Road“ zwischen Kabul und Dschalalabad, AfghanistanEnglish: Jalalabad Rd., highway from Kabul to Surobi and Jalalabad, Afghanistan. Retrieved from https://commons.wikimedia.org/wiki/File:Jalalabad_Road_rock_fall.jpg

Zell, H. (2013, June 6). Canyons and Glaciers Along the Northwest Coast of Greenland. Retrieved February 16, 2019, from http://www.nasa.gov/mission_pages/icebridge/multimedia/spr11/dscn1935-ms.html



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Introduction to Physical Geography by R. Adam Dastrup is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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