Extreme Events Flashcards
What was the explanation given to the shaping of landforms during the 18th and 19th centuries?
Catastrophism - the influence of god and miracles produced large events that drastically altered the landscape
What is gradualism?
the idea that the earths changed very slowly over long periods of time.
Who established the idea of gradualism?
Hutton and Lyell
What did gradualism lead to?
The recognition that the world could be billions of years old as well as the idea that ‘the present is the key to the past’.
What is ‘geomorphic work’?
the measure of total sediment transported by aa river annually.
What conclusion did Hovius et al. 1997 reach?
A negative linear relationship between area affected and frequency of event. this meant that the neither extreme and rare events nor small and frequent events dominated landscape evolution. They were proportional
What conclusion did Wolman and Miller 1960 reach?
That for sediment load and bed load the most amount of work (magnitude x frequency) was achieved during events that occurred every two years. This suggested that these relatively rare events played the most important role in creating geomorphic work
What conclusion did Leopald and Wolman 1957 reach?
A slight, non-linear negative relationship between bankfull discharge and channel slope gradient. They suggested that this meant the stream power of bigger flat rivers was much bigger than small steep rivers.
What happened in the Missoula Floods?
The Laurentide Ice Sheet blocked Missoula glacial lake that prevented flow out in to the pacific. Eventually the lake infilled so much that it overflowed unleashing a ~3million Cumecs discharge upon Wahsington.
What was the impact of the Missoula floods?
Huge waterfalls that today have dried up such as dry falls and instead have converted in to gorges.
How fast is it predicted that the Missoula floods travelled?
80mph
How many times did floods on the scale of Missoula happen due to the Laurentide ice sheet changes during glacial periods?
25-30 times every period
What happened in the English Channel Floods?
Glacial periods also caused there to be huge discharges around 1 million Cumecs in to the English channel
Who predicted the English Channel floods?
Gupta et al., 2007
What were the discharges of floods that happened on Mars?
~60million Cumecs - 1 billion Cumecs
