Presentation on theme: "The Influence of Geology in the Development of Glacial Landforms."— Presentation transcript:
1The Influence of Geology in the Development of Glacial Landforms.
2Rock character (lithology) Porosity / perviousness allows water to enter rock and assist plucking processWhat landform?
3Earth movement processes e.g. isostatic uplift in post glacial times Raised Beach at Low Tide - Little Gruinard, Scotland
4Weathering – freeze thaw creates scree. E. g Weathering – freeze thaw creates scree. E.g. post glacial north Wales on Snowdon.Most effective in uplands created by uplift. With well jointed rocks.
5Mass Movements – affected by steepness of slope, porosity, Weathered / rock layering e.g. Solifluction on gentle periglacial slopes (lobes), falls on steep slopes (scree)Solifluction in weathered layer above permafrost layer
6Tal-y-Llyn – a landslide dammed lake (below Cader Idris
7Erosion more effective on steep slopes e.g. mountain glaciers in the tropics (Pakistan Himalayas)
8Differential erosion of hard and soft layers Produces Paternoster Lakes, Washington State, USA (Mount Rainier)
9Almost vertically tilted bedding planes allowed steep back wall to Llyn Cau, Cader Idris to develop
10Resistant sill of igneous rock deflected the glacier from Llyn Cau round to the east
12Fault controlled valley of Tal-y-Llyn effectiveness of erosiondirection of erosion
13Striations –material carried in the ice Striations –material carried in the ice. Scratches caused by resistant hard material in the ice by the process of abrasion
14Less resistant material gets ground down by abrasion into rock flour. Lake Louise, Canada has a turquoise colour due to ground down rock flour sediment in the meltwater.
15Transport and Deposition – change of gradient perhaps from high land hard rock to lowland softer rockKnock and Lochan landscape of eroded resistant roche moutonnnees (knocks) and eroded hollows (lochans)
16Fluvioglacial deposits – coarser gravels are deposited nearer the snout and finer material is transported further away before deposition.Braided meltwater stream depositing outwash just beyond the ice front of a glacier