GL29 Introduction to glaciofluvial landforms Flashcards
What is the name of the interglacial we are currently in?
The interglacial we are currently in is called the Holocene.
What is the name of the last glacial period, and when did it end?
The last glacial period is called the Devensian glaciation, and it ended approximately 11,700 years ago.
What is the name of the glaciation that affected the UK and Ireland?
The glaciation that affected the UK and Ireland is the Devensian glaciation.
What is the name of the glaciation that affected parts of North America?
The glaciation that affected parts of North America is the Wisconsin glaciation.
What is the post-glacial period, and when did it begin?
The post-glacial period is the period after the last glacial period when glaciers were predominantly retreating with negative mass balances. It covers the end of the last glacial period and the current interglacial. The post-glacial period began around 11,700 years ago.
What is the impact of relief on the different ice lobes and till sheets?
Highland areas diverted the ice lobes to follow low flat areas, which affected the location of glacial rivers and the deposition of till sheets. For example, the Des Moines Lobe advanced east and deposited clay-rich soils over 160m deep, while the Wadena lobe created the terminal moraine and Wadena drumlin field.
How does geology affect the rate of erosion and the landscape in Minnesota?
The geology of the rock that the ice sheet is on will affect how quickly the rock gets eroded, which would affect the thickness of the ice sheet. North Minnesota is part of the Laurentian Shield and is underlain by alternating bands of resistant igneous rock and weaker sedimentary rock. The ice sheet eroded many pyramidal peaks in the hard igneous rock, while the weaker rock was eroded more to create deep lakes.
What are the characteristics of glacio-fluvial sediment and landforms?
Glacio-fluvial sediment is generally smaller and sorted than glacial till, and is smooth, rounded and stratified due to the contact with water and by attrition. Glacio-fluvial landforms can be identified by five distinct characteristics of the sediment they are formed from, which are stratification, sorting, imbrication, shape, and grading.
How can outwash be distinguished from glacial till?
Outwash can be distinguished from glacial till by being generally smaller, smooth, rounded, sorted, and stratified. Glacial till, on the other hand, is deposited directly by the glacial ice and is unsorted, poorly stratified and not rounded.
What are the impacts of climate on the landscape in Minnesota?
The extended period of cold temperatures combined with continued precipitation during the Wisconsin glaciation led to the advance of the ice sheet up to 4km thick. This meant the ice sheet covered extensive areas, was not constrained to high altitude valleys, and had an extremely erosive impact on the landscape of Minnesota. The movement of the ice caused erosion and the formation of ellipsoidal basins, which lead to the creation of giant proglacial lakes when the glacial period ended.
