Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens slowly, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it plucks material from the riverbed. Whirlpools created in the turbulence as well as sand and stones carried by the watercourse increase the erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one and half meters per year.
Often, the rock stratum just below the more resistant shelf will be of a softer type, meaning that undercutting due to splashback will occur here to form a shallow cave-like formation known as a rock shelter under and behind the waterfall. Eventually, the outcropping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by attrition as they collide with each other, and they also erode the base of the waterfall by abrasion, creating a deep plunge pool or gorge.
Streams become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom. Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by earthquakes or landslides or volcanoes can cause a differential in land heights which interfere with the natural course of a water flow, and result in waterfalls.
A river sometimes flows over a large step in the rocks that may have been formed by a fault line. Waterfalls can occur along the edge of a glacial trough, where a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted. The large waterfalls in Yosemite Valley are examples of this phenomenon, which is referred to as a hanging valley. Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other. Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall (which depends on both the waterfall's average flow and its height) using a logarithmic scale. Class 10 waterfalls include Niagara Falls, Paulo Afonso Falls and Khone Falls.
#WaterfallWednesday #gif #nature #naturegifs #photography #travel #naturephotography #travelphotography #photooftheweek #trending #trendingnow #picoftheweek #spring #spring2014 #springphotography #springphotos #springpictures #springpics #naturephotos
Site-ul anunţul urmărit penal după ce mai
7 Nis 2015 - Site-ul anunţul este urmărit penal pentru proxenetism, după ce procurorii au stabilit că prin intermediul acestuia erau racolaţi "clienţi" de www.anuntul-galben.ro
- International Medical University MalaysiaAssociate Professor, 2008 - present
- Gandhara University PakistanAssistant Professor, 2000 - 2008
- Khyber College of DentistryBachelor of Dental Surgery, 92 - 95
- University of MalayaConservative Dentistry, 98 - 2000
- University of PeshawarPG Diploma in Health Planning & Managment, 2 - 2
- Gandhara UniversityPublic Health, 5 - 6
- Snakes and Ladders
- Critical Ops
Google Released A New Educational Tool to Wirelessly Share Computer Scre...
July 17, 2016. Google Cast for Education is a new Chrome app from Google to help teachers and students wirelessly share their computer scree
See What Happens When You Eat Garlic On an Empty Stomach ‹
Did you know that eating a whole head of garlic a day does miracles for your body? Garlic – a simple ingredient with amazing health benefits
Seven Characteristics of Good Learners | Faculty Focus
Good teachers model this kind of learning for their students, which makes me believe “good learner” belongs on those lists of good teacher c
Watch This Multi-Billion-Dollar Industry Evaporate Overnight | LinkedIn
Imagine an industry where a few companies make billions of dollars by exerting strict control over valuable information -- while paying the
Five Lies That Could Be Ruining Your Career (and your Life) | LinkedIn
We humans are really great at telling ourselves stories. That voice we hear in our head recites some pretty interesting narratives so often
The Pakistan zeitgeists: A nation through the ages
NFP takes us on a journey across Pakistan
Q5 Kid Mobile Phone With GPS Tracking (Blue+White, Q5 Warranty)
Only at RM299! Grab it now!
Der erste Lernstift, der vibriert, wenn man sich verschreibt!
Der Lernstift erkennt die Schreib-Bewegungen bzw. die Zeichen und Worte. Damit kann der Lernstift z.B. Rechtschreibungs- und Grammatik-Fehle
NA panel to PMDC: ‘Revoke all recent decisions’ – The Express Tribune
Disapproves of council’s functioning despite notice for termination .
9 Things You Should Tell Your Boss At Your Next Performance Review
Because your review is also a time to share your own goals (and even suggestions!) for the future with your boss.
A touch of inspiration runs both ways as Sean Penn visits shrine and Edh...
The Edhis were unaware of who was coming to visit them.