The glacial buzzsaw is a

hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

claiming

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

by warm-based glaciers is key to limit the height of mountains above certain threshold altitude. To this the hypothesis adds that great mountain massifs are leveled towards the

equilibrium line altitude Glaciology (; ) is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, clima ...

(ELA), which would act as a “climatic base level”. Starting from the hypothesis it has been predicted that local climate restricts the maximum height that mountain massifs can attain by effect of uplifting tectonic forces. It follows that as local climate is cooler at higher latitudes the highest mountains are lower there compared to the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referr ...

where glaciation is and has been more limited. The mechanism behind the glacial buzzsaw effect would be the erosion of small glaciers that are mostly unable to erode much below the equilibrium line altitude since they do not reach these altitudes because of increased

ablation Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft material for a ...

. Instead, large

valley glacier A valley is an elongated low area often running between Hill, hills or Mountain, mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers ...

s may easily surpass the equilibrium line altitude and do therefore not contribute to a glacial buzzsaw effect. This is said to be the case of the

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and g ...

ice field An ice field (also spelled icefield) is a mass of interconnected valley glaciers (also called mountain glaciers or alpine glaciers) on a mountain mass with protruding rock ridges or summits. They are often found in the colder climates and highe ...

s where lack of buzzsaw effect results in rapid

tectonic uplift Tectonic uplift is the geologic uplift of Earth's surface that is attributed to plate tectonics. While isostatic response is important, an increase in the mean elevation of a region can only occur in response to tectonic processes of crustal th ...

rates. Mountains massifs proposed to be subject to a glacial buzzsaw effect include the mountains of southeast Alaska, the

Teton Range The Teton Range is a mountain range of the Rocky Mountains in North America. It extends for approximately in a north–south direction through the U.S. state of Wyoming, east of the Idaho state line. It is south of Yellowstone National Park and ...

of Wyoming and the

Dauphiné Alps The Dauphiné Alps (french: Alpes du Dauphiné) are a group of mountain ranges in Southeastern France, west of the main chain of the Alps. Mountain ranges within the Dauphiné Alps include the Massif des Écrins in Écrins National Park, Belledon ...

of France. Authors such as Egholm and co-workers have claimed that the glacial buzzsaw effect can explain mountain altitudes across the globe. Some of the mountain massifs experiencing the highest uplift rates are those for which glacial buzzsaw effects are discarded. The concept has been criticized, as measured erosion rates in the

Pyrenees The Pyrenees (; es, Pirineos ; french: Pyrénées ; ca, Pirineu ; eu, Pirinioak ; oc, Pirenèus ; an, Pirineus) is a mountain range straddling the border of France and Spain. It extends nearly from its union with the Cantabrian Mountains to ...

do not indicate a general drive towards any certain level. In the case of Norway the elevated

paleic surface The paleic surface or palaeic surface ( no, paleiske overflaten, ) is an erosion surface of gentle slopes that exist in South Norway. Parts of it are a continuation of the Sub-Cambrian peneplain and Muddus Plains found further east or equivale ...

has been proposed to have been shaped by a glacial buzzsaw effect. However this proposal is difficult to reconcile with the fact that the paleic surface consist of a series of steps at different levels. Further

glacial cirque A (; from the Latin word ') is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic , meaning a pot or cauldron) and (; ). A cirque may also be a similarly shaped landform ...

s, that in the buzzsaw hypothesis contribute to belevel the landscape, are not associated to any paleosurface levels of the composite paleic surface, nor does the modern ELA or the Last Glacial Maximum ELA match any given level of the paleic surface. The elevated plains of

West Greenland Kitaa, originally Vestgrønland ("West Greenland"), is a former administrative division of Greenland. It was by far the most populated of the divisions, being home to almost 90% of the total population. The divisions were de facto replaced by st ...

are also unrelated to any glacial buzzsaw effect.

Footnotes

References

{{reflist Glacial erosion landforms Erosion Mountain geomorphology Hypotheses

See also

Footnotes

References