Badlands - Cathedral Gorge Case Study
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Not a "stand up" presentation - more a revision narrative or maybe a homework exercise. A new location to stimulate the kids' interest. Anyway, download and disaggregate as you wish. Enjoy.
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Badlands - Cathedral Gorge Case Study
Editor's Notes
- Badlands are a good example of extreme erosion, transportation and deposition by water. The resulting landforms and drainage patterns are spectacular to say the least.
- Badlands wear their fluvial origins on their sleeves. Not a drop of water to be seen but the evidence is everywhere. Cathedral Gorge State Park in Nevada, USA is our case study area.
- Vertical erosion by streams is called “downcutting”. Slot canyons, such as this example, form where the downcutting is rapid. (Summer downpours and Spring snowmelts do the damage at Cathedral Gorge.)
- Cathedral Gorge sits in a basin which is referred to as Meadow Valley on local maps.
- There is evidence of rockslides and very limited talus creep at Cathedral Rock. Mudflows and earthflows are also found, but are fluvial in origin (formed by moving water) and are not the result of mass movement.
- The main agent of erosion at Cathedral Gorge is undoubtedly moving water. All three mechanisms combine to form this “badlands” topography.
- Sustained concentrated flow can eventually produce rills, microchannels a few centimetres in depth and width. If the rills survive, they eventually form perennial gullies.
- The semi-arid climate leads to intermittant drainage and means that the evidence of flooding events are there to be examined until the next flood event!
- Silt sits between sand and clay in terms of size. Sand particles are 0.05 to 2 mm in diameter, silt particles are 0.002 to 0.05 mm in diameter and clay particles are less than 0.002 mm in diameter.
- Once the cap rock or more resistant layer has been eroded away completely cliff retreat takes place on all sides and aretes and pyramidal peaks are formed. Hence the name “Cathedral Gorge”.
- This striking landscape meant that Cathedral Gorge quickly became a popular area for hiking and picnicking and in 1935 was designated a State Park.
- Numerous slot canyons form a major attraction in the south east part of the park. The slots are the result of rapid downcutting in soft friable sediments – mainly siltstone.