The Origin of Dirt Cones on Glaciers

Abstract

The characteristics and probable development of dirt cones on Vatnajökull (Iceland) are described. Thick accumulations of debris protect the ice beneath them from ablation, whereas thin ones accelerate the process. Under given conditions of ablation, the nature of the debris covering is the deciding factor—in particular its radiation absorption coefficient, conductivity and thickness. Contrasts are noted between the dirt cones of Vatnajökull and those of other glaciers. The nature of the debris and of the ablation varies greatly from place to place, but all dirt cones result from differential ablation.

Lake Miers, South Victoria Land, Antarctica

“…Similar dirt cones have been previously observed on glacier ice and on snow (Swithinbank, 1950;Lliboutry, 1953;Wilson, 1953;Krenek, 1958;Ashwell and Hannwell, 1966), but these were necessarily transient phenomena, whereas U.S. Navy aerial photographs show that the cones on Lake Miers have existed in similar form for at least 10 years. They are probably much older than that and are changing slowly in shape as debris slips from their sides to form new accumulations and thence eventually new cones.…”

Circular moraine features on the Varanger Peninsula, northern Norway, and their possible relation to polythermal ice sheet coverage

“…The protected ice blocks get a conical shape. These so-called ''dirt cones'', conical ice blocks covered with a till layer with heights of up to 85 m, were observed on Himalayan glaciers (Swithinbank, 1950). During the slow melting process of these conical dead-ice blocks, till slides down the margins of the cone, forming a ring on the ground.…”

Ablation Cones on Sidujökull, Iceland

“…For example, Workman (1907Workman ( , 1909Workman ( , 1914 found them in the Himalayas, Phillip (1914) and Seelheim (1910) in Spitsbergen, Krenek (1958) in New Zealand, and Lliboutry (1958) in Universidad glacier in the Chilean Andes. According to Swithinbank (1950), Russel (1893) also met these forms. However, it follows from the context that Russel actually wrote about ice-cored moraines.…”

“…They have developed under optimal conditions due to abundance of volcanic and morainic material in the ablation zones. Swithinbank (1950) wrote that it was not unusual to see hundreds of these forms, 1 to 3 metres high, placed on the glacier margins and resembling heaps of ashes. Palsson (Charlesworth, 1957) mentioned the forms occurring in Iceland, Thorodssen (1906) observed them in Skaftarjokull and called them Eispyramiden, and Kosiba (1938) in Myrdalsjb'kull.…”

“…Palsson (Charlesworth, 1957) mentioned the forms occurring in Iceland, Thorodssen (1906) observed them in Skaftarjokull and called them Eispyramiden, and Kosiba (1938) in Myrdalsjb'kull. Iwan (1935), Keindl (1932), Lewis (1940), Nusser (1935), Oetting (193O), Spethmann (1912), Swithinbank (1950), and Bout (1956Bout ( , 1958 mentioned these forms in their works and tried to explain their origin. Undoubtedly, the most precise observations and conceptions of their origin can be found in the works of Lewis, Swithinbank, Bout and Krenek. During …”