How do potholes form?
535872
You should show how ice expands and can damage roads and concrete... very stiff materials.\nCheck out the links\n\nOh yes and don't forget about wear and tear cars and other vehicles can cause... I am not sure how much time you have for your science fair project... typical road wear studies can last for years.
1129951
When it rains, it can do one of two things... be absorbed into the ground OR runoff into low-lying areas.\n\nSeveral factors can determine whether rain will become groundwater or runoff.\n\n1.)Type of soil - sandy soils are more porous and allows water to pass through more easily than those such as clay soils. Therefore soil type will determine drainage.\n2.)Type & amount of vegetation - Vegetation can either allow runoff by inhibiting drainage or can allow for the slow down of water movement which would allow it to be absorbed. It just depends on how much & the type.\n3.)Slope/steepness of an area - steeper areas are more likely to lead to runoff rather than absorbtion.\n4.)Ground saturation levels - if the ground is already saturated w/ water it will not hold anymore & will lead to runoff.\n\nDepth can be determined by...\n1.)Depth of bedrock or basement rock - This could be a nonporous/impermeable rock which just means that it won't allow water to move through. If the bedrock type won't allow drainage then that is where the water will stop.\n2.)The depth of the water table - if the water table is deeper, then the deeper the water will have to travel before reaching it.
172827
There are a couple ways. Hot spots can build up islands through volcanic activity, like Hawaii. Some islands can be created by subduction volcanism (Japan). Other islands can be uplifted at convergent or possibly transverse plate boundaries.\n\nIslands can also be created by erosion and inundation, as in a case of sea level rise where the water covers low lying areas while higher areas get "separated" from the land by water (St. Lawrence Island in Alaska). Glaciers can scour channels around large land masses, then recede and the channels can become filled with water to surround the land masses and make them islands. Manhattan Island was actually created by a continental glacier pushing a bunch of sediment out into the ocean and then receeding (it is a moraine).\n\nSome islands can be created purely by sediment deposition, such as those at the mouths of deltas. \n\nScleractinean coral will also form islands (atolls) even as the land around them recedes because they require sunlight to live. Coastal erosion is also known to produce offshore bars which, if big enough, can be vegetated and become islands.\n\nRivers can also meander around bits of land on the floodplain and cut them off from the rest of the earth, forming islands.
228898
I had the same thing keep happening to me, so I took a big,long, steel pipe and dug down about 3 feet deep and concreted it in the hole. Then I covered the concrete with dirt,built a square tube out of 1x4 boards and placed over the pipe. Then nail the mailbox to the boards, now your mail box looks like any other mailbox! Let someone run over this mailbox and they can say good bye to their car!lol
276560
This is sedimentation. It isn't foundations sinking, although that can happen. It's weathering products. Soil production is one way that things can become buried, as pointed out in the first answer, but for the most part, it is windblown, mass-movement, or water deposition that puts things that were initially on the surface underground.\n\nIt is important to note that there are regions of net deposition and those of net erosion, so not everything will always become buried. Sometimes it is subject to weathering itself. Large stone amphitheaters will fall apart and the pieces will be subject to weathering with will make them look like shapeless boulders. The only other way to get large boulders anywhere is by downhill mass movement, glacial transport, flash floods or by people putting them there.
1115641
If it hits sand, it will often make glass.  It makes the ground very hot for a short time, having so much moisture around it draws the heat away quickly.
580033
You've probably seen the pictures of a grid with a giant funnel extending infinitely downward.  That's not the shape of the hole itself, but a map of the curvature of space near the singularity.  The singularity, or "hole" itself is a point of infinitely large density and infinitely small size.
581235
First, to all those who don't know what a dike is...\n\nA dike or dyke is an intrusive igneous body of rock.\n\nMagma will branch out from the magma chamber though breaks or fractures in the pre-existing rock layers. When it cools, intrusive igneous rocks form.\n\nDIKES, in particular, form when magma intrudes into existing rock strata or layers & then hardens. SILLS form in much the same way with one difference.\n\nDIKES cut across strata whereas SILLS form parallel to the rock layers.
149401
when it rains, it pours.\n\nHope you don't live on/near a hillside.
222466
Dave in NC answered it perfectly.  Ill just add, if you are asking why tornados form over land- The rapid increase in heat needed to cause formation of tornados generally occurs only over land, since water modulates changes in heat.  However, sometimes they do form, but they are called waterspouts, and usually occur near hurricanes.
141648
It is formed by heat pressure
323653
Its due to some micro-organisms in the soil.\nTheir sporebags rupture on contact with water, and they enter the air.
558807
Most tornadoes follow a recognizable life cycle.[6] The cycle begins when a strong thunderstorm develops a rotating mesocyclone a few miles up in the atmosphere, becoming a supercell. As rainfall in the storm increases, it drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the rotating mesocyclone towards the ground with it.\n\nAs the mesocyclone approaches the ground, a visible condensation funnel appears to descend from the base of the storm, often from a wall cloud. As the funnel decends, the RFD also reaches the ground, creating a gust front that can cause damage a good distance from the tornado. Usually, the funnel cloud begins causing damage on the ground (becoming a tornado) within minutes of the RFD reaching the ground.\n\nInitially, the tornado has a good source of warm, moist inflow to power it, so it grows until it reaches the mature stage. During its mature stage, which can last a few minutes to more than an hour, a tornado often causes the most damage, and can in rare instances be more than one mile across. Meanwhile, the RFD, now an area of cool surface winds, begins to wrap around the tornado, cutting off the inflow of warm air which feeds the tornado.\n\nAs the RFD completely wraps around and chokes off the tornado's air supply, the tornado begins to weaken, becoming thin and rope-like. This is the dissipating stage, and the tornado often fizzles within minutes. During the dissipating stage, the tornado becomes highly influenced by the direction of surface winds, and can be blown into fantastic patterns.\n\nThough this is a widely-accepted theory for how most tornadoes form, live, and die, it does not explain the formation of smaller tornadoes, such as landspouts, long-lived tornadoes, or tornadoes with multiple vorticies. These each have different mechanisms which influence their development—however, most tornadoes follow a pattern similar to this one.
173251
A cumulonimbus cloud forms in rising air (updraft).  The air cools as it rises, and at a certain point the water vapor in the air condenses into water droplets, forming a cloud.  Around a large Cb there is often downdraft - the air gets warmer as it subsides, and any water droplets (=clouds) will evaporate.
975582
You can't tell by just stepping outside, unless you see a funnel cloud or something.  Tornadoes are usually created from cold fronts or occluded fronts.  You have very warm air ahead of the front, and very cool air behind it.  The difference in the air temperature pushes air up, creating an updraft.  Bottom line, tornadoes are caused by warm and cool air in the same area.  And you have to have very strong winds in the upper atmosphere.  70 to 80 mph.  That helps with the updraft.
476271
chemical erosion (dissolving elements from the rocks) deepen the cracks between the rocks creating the pavement effect
711017
A destructive plate boundry causes one plate to be subducked below another, (sucked under basically) this causes it to melt and then rise to the surface where it forms the Mount Pelee volcano\n\nHope that helps