Gallery

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Photo glossary
Animations

Photo glossary

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A

Accumulation

The process of building up a layer of snow, refrozen meltwater, slush and firn that survives the melt season to contribute mass to the glacier. Due to the extreme relief of the greater Himalaya, some glaciers main source of accumulated mass is through avalanche deposits. The photo shows an avalanche descending from a hanging glacier above Khumbu Glacier.

Avalanche descending from a hanging glacier above Khumbu Glacier

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B

(Glacier) Bed

The bedrock or layer of rock debris on which the glacier sits and flows. The bedrock over which Lobuche Glacier used to flow is visible in front of its clean­ice terminus.

Retreating Lobuche Glacier exposing bedrock

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C

Calving

The process whereby blocks of ice become detached from the glacier. Photograph shows an ice cliff calving event on the Khumbu Glacier.

Calving of an ice cliff on Khumbu Glacier

Cirque

An open amphitheatre like feature with steep sides and back wall formed as a result of glacial erosion by a small glacier. Multiple cirque glaciers may converge to form a main glacier tongue.

Cirque visible from Khumbu Glacier

Crevasse

A wedge-shaped opening formed due to extensional flow. Crevasses can be tens of metres deep and pose a hazard to glacier travel when snow covered. Photograph taken of the Argentière Glacier terminus.

Crevasses on Argentière Glacier

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D

Debris cover

A debris-covered glacier can have debris ranging from fine sediment to car-sized boulders covering the surface of the ice. A thin layer (up to several cm) promotes melt whereas a thick layer insulates the ice beneath. Photograph shows debris cover on and around an ice cliff on the Khumbu Glacier.

Debris-covered ice cliff on Khumbu Glacier

Downwasting

Downwasting or thinning is a common response of heavily debris-covered glaciers to climatic warming. Shallow gradients and thicker debris cover at lower elevations means the highest melt rates occur higher up-glacier. Therefore, rather than retreat up-valley, the glacier gets thinner year-on-year. Photograph taken of the Khumbu Glacier.

Surface lowering (thinning) of the debris-covered Khumbu Glacier

Draining pond

Supraglacial ponds can drain englacially, leaving exposed basal sediment. Other evidence of drainage events includes collapsed ice around the pond margins or raised undercut notches on ice cliffs. Photographs taken on Khumbu Glacier.

Supraglacial pond that has drained englaciallySupraglacial pond and undercut notches

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E

Englacial debris

Debris that has been incorporated into the glacier through burial in the accumulation zone or after falling into a crevasse.

Englacial debris visible in an ice cliff

Everest/ Sagarmāthā/ Chomolungma

The highest mountain on Earth at 8848 m (29,029 ft) elevation. Tenzing Norgay and Edmund Hillary made the first official ascent in 1953 using the southeast ridge route.

Everest and the Khumbu icefall

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F


G

Glacial Lake

A large body of water found in front (proglacial) or at the surface (supraglacial) of a glacier. The photo shows Imja Tsho, a large glacial lake in the Dudh Koshi catchment.
Photo by Lauren Knight.

Imja Tsho glacial lake in the Everest region

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H

Hanging glacier

Hanging glaciers are small ice bodies that cling to the high, steep mountain sides. They may contribute mass to larger glaciers below through avalanching.

Hanging glacier above Khumbu Glacier

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I

Ice cliff

Cliffs range in height from several to tens of metres and are often associated with supraglacial ponds. The bare or lightly debris covered surface create high melt rates. Photograph taken on the Khumbu Glacier.

Ice cliff and supraglacial pond on Khumbu Glacier

Icefall

A heavily crevassed section of a glacier where rapid flow is often promoted as ice flows over a steep or narrow area of bedrock.

Khumbu icefall

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J


K


L


M

Moraine

Distinct mounds or ridges of debris deposited by the glacier. They are located at glacier periphery, or between the flow units of glaciers formed by multiple tributaries. Their longevity makes them ideal markers of former glacier extent.

Moraines above the village of PhericheMoraines below Lobuche Glacier

Moulin

A water-formed plunge shaft where meltwater enters the glacier and may travel to the bed in a series of steps. Photograph taken on Mer de Glace Glacier.

Moulin on Mer de Glace Glacier

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N


O

Open ROV

An underwater exploration robot on a long tether that can measure depth, temperature, and record live HD video.

OpenROV underwater exploration robot

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P


Q


R


S

Supraglacial pond

Water collecting in depressions can locally enhance glacial melt by absorbing solar radiation and transmitting this energy to the ice below, or englacially if the pond drains. Photograph taken on Khumbu Glacier.

Supraglacial pond surrounded by ice cliffs and debris-covered ice on Khumbu Glacier

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T

(Glacier) Table

A boulder perched on a column of ice. The boulder protects the ice beneath from melt by direct sunlight.

Perched boulder

Trimline

A consistent linear feature on a hillside marking the boundary between well-vegetated ground that has not recently been covered by glacier ice and poorly vegetated, steep ground that has been recently inundated by glacier ice. The most prominent trimlines visible in the Khumbu valley are from the Little Ice Age.

Trimline marking the previous extent of glaciation in the Everest region

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U


V

Vegetation

Towards the terminus of some debris covered glaciers, the surface may have been stable for long enough to allow the development of soil and the growth of pioneer plants. A small area of the Khumbu Glacier bares small plants.

Plants on Khumbu Glacier

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W


X


Y


Z


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Animations

Glacier dynamics

 

Glacial lakes

Supraglacial ponds:

TopOutburst floods

Modelled landslide-dammed lake outburst flood along the Marsyangdi River in NepalSimulation of a landslide-dammed lake outburst flood along the Marsyangdi River in Nepal. A river-blocking landslide occurred in 2015 after the Gorkha earthquake, leading to concern of a potential outburst flood. However, this did not occur. The simulation was produced to demonstrate the benefits of fine-resolution topography.

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