High Energy Events And longer intervening periods of relative stability How do they influence the evolution of glaciated landscapes?

High Energy Events

And longer intervening periods of relative stability

How do they influence the evolution of glaciated landscapes?

The northward drift of continents in plate tectonic movements may restrict oceanic circulation leading to cooling – and an Ice Age. A new High Energy event is caused.

Long Time scale

(00,000s years

Large Area Affected

Tectonic Cause

Long Time scale(00,000s years

Large Area Affected

Tectonic Cause

Also plate collisions can lead to uplift of Young Fold Mountains – which are high enough to support glaciers even in tropical latitudes during interglacial periods. A High Energy Event.

Long Time scale(00,000s years

Large Area Affected

Climatic Cause

In the Ice Ages places like Britain were covered in Ice Sheets and spectacular landforms were carved out by erosion and depositions occurred on lowland. Each Ice Age is a High Energy Event.

Interglacials are long periods of relative calm when little change happens

Save for isostatic adjustments (tectonic)

Isostatic adjustment leads to features like raised beaches along the coast

With the climatic change of the interglacial a return to fluvial erosion occurs. With misfit rivers like Nant Cadair in hanging U shaped valleys.

Short Time Scale

Years, seasons, hours

Smaller area

Tectonic Cause

Alluvione or glacial avalanche in 1970 triggered by an earthquake. 20,000 people killed in Yungay. Mount Huascaran, Peru.

Short Time Scale

Years, seasons, hours

Smaller area

Tectonic Cause

In Iceland jokulhlaup (outburst floods) are triggered if volcanoes erupt under ice caps e.g Grimsvotn volcano under Vatnojukull ice cap 1997.

Global Warming Fills Glacial Lakes to Bursting At least 44 glacial lakes high in the Himalayas are filling so rapidly they could burst their banks in as little as five years, an international team of scientists has found. E.g. Bhutan, Nepal Monitor by remote sensing

Short Time Scale

Years, seasons, hours

Smaller area

Climatic CauseGLACIAL LAKE OUTBURST FLOODS (called Debacles in Switzerland)

Short Time Scale

Years, seasons, hours

Smaller area

Climatic Cause

AVALANCHE

A seasonal risk – often occur with warming in Spring. Needs careful management.

Short Time Scale

Years, seasons, hours

Smaller area

Climatic Cause

VARVED CLAYS

Higher Energy in summer when melting occurs and water flows into lakes so coarse sediments deposited. Calm in winter freeze up so fine clays get deposited.