These smaller types of potholes are very common and are not very deep. They often have evidence of minor drilling. They form due to the presence of water above and below ground and some type of compression, either a heavy vehicle driving over the surface of a road or bouncing boulders travelling downstream during a flood event. If the plucking out of rock material is aided by rapidly moving water during a flood, this facilitates the enlargement and drilling of the pothole. Kolk-plucked potholes are assisted by underwater vortices which enlarge them and do the rounded carving of the rock. See http://en.wikipedia.org/wiki/Kolk for information on kolk-plucked potholes.
Click a link to see original photos
From left to right: Cracks in rocks called joints are common everywhere on Earth - water penetrates them and begins various erosional processes; Example of a joint pattern that sets up the rock to start disintegrating; Rock disintegrating according to a joint pattern sets the stage for later plucking to start pothole formation
From left to right: A large crack that is subject to periodic flooding has many potholes inside - Antelope Slot Canyon & LakePowell aerial, AZ - Peter L Kresan photographer; A small crack in a roadway – this is like a mini slot canyon; golden reflection
From left to right: Traction and saltation of river boulders, cobbles and pebbles help initiate the formation of potholes in streambeds by contributing to the further disintegration of rock material and by plucking out loose rock material; Saltation - the bouncing/jumping of rocks as they move downstream initiates the formation of potholes as they hit weak spots along the bottom of the streambed – go to the link for animation; Traction - tumbling of rocks along the bottom of a streambed is like the impact of vehicles upon the road surface and initiates the formation of potholes – go to the link for animation
From left to right: An immature streambed broken along joint planes will not have very many potholes yet - Ringing Rocks Park, Penn. May 8 08 photos ©Nancy J. Ondra; a mature stream with well-rounded rocks will be more likely to have potholes; Porcupine mountains waterfall- Michigan....full of potholes!
From left to right: A stream bed with a pavement of small potholes in Hercules Glade Wilderness, Missouri; Kharir River, India - a shallow pothole that looks like it has been drilled; Pothole in sandstone that looks like it has been drilled - Raquette River, Adirondacks
From left to right: River Potholes at Niagara Falls - a nearly perfect scribed circle is seen center right but only half of a pothole has chipped out. Will multiple blows in almost the same spot make a round pluck? Each stream will have a percentage of round potholes to other random pluck shapes; Potholes in basalt boulders, South Esk Gorge, Launceston, Tasmania “ ...most potholes probably get started by a pressure related disintegration process and are later exposed by erosion...” Douglas E. Cox; standard theory of pothole deepening once the hole is big enough to create a strong vortex
From left to right: potholes - Bonas Defeat, N Carolina; Rainbow Falls, Watkins Glen, New York
From left to right: potholes - Fish River Falls, Maine – a double merged pothole; a shallow Kolk plucked pothole of eastern Washington scablands - a kolk is an underwater vortex; View from the top of Fossil Falls showing multiple small potholes and other associated water-eroded topography , with the foothills of the Sierra Nevada Mountains in the background
On the left: fossilfalls10
From left to right: fossilfalls23; Glacial Potholes | Atlas Obscura – Massachusetts - click on picture at this link for more pothole pictures; The curious case of half a pothole on one side of a joint crack and not on the other side. The larger pothole to the right is also a strange shape. I do not know how deep these potholes are. – Ausable River, NY
From left to right: Fossil Falls, CA - a muddy double pothole; Fossil Falls close-up of water carved volcanic rock, CA – as more material is removed and as potholes connect and drill thru their bottoms, more complex patterns of carved rock evolve; Arches like this one at Fossil Falls, CA appear in more complexly eroded water-carved topographies – person with white hat on for scale – better arch pictures to follow
From left to right: Taylor Falls, Minn; Desert Potholes - sandstone - Green River, Utah
More pictures of more potholes at http://www.sentex.net/~tcc/pothole.html This link also links to other pothole articles asking good questions about pothole formation.
© Laura Fitzpatrick 2014