Mima Mounds

Across the planet, and especially the US, there are row upon row of perfectly made seemingly natural but completely inexplicable mounds. They are called the Mima Mounds. And no one really has a good grasp on how they were created.




The majority of them are found in the US, especially in Washington State and the northwest.


All of the mounds, across the US and all around the world, share very similar features. They are about 3-6ft tall an laid out in very evenly spaced diagonal rows. However excavation of the mounds have shown that a) they can have very different soil structures, and b) there are no aliens or burial sites in the mounds. At least not that anyone has been able to find a trace of.

this is the best of the explanations wikipedia has to offer:
http://en.wikipedia.org/wiki/Mima_mounds

Pocket Gophers

One major theory concerning the origin of Mima mounds argues that they were created by pocket gophers—small, burrowing rodents with fur-lined "pockets," or pouches, in their cheeks. The theory is that gophers tunneling into loose soil run into a gravel layer below. Unable to burrow any farther, the gophers start building upward and outward. The theory's author, George Cox, a retired zoologist at San Diego State University, says that a gopher family often can move up to 5 tons of earth a year.^{[citation needed]} That's one-twentieth of the soil in an average Mima mound.^{[citation needed]} Cox also asserts, most North American mounds are in gopher territory, and many gophers actually live in mounds. However, the only pocket gophers ever spotted on Mima Prairie built their burrows between the mounds, not in them. It is unclear whether gophers created the mounds or migrated to them because the mounds provided handy home sites.

[edit] Alien Origin

Another major theory concerning the origin of mima and prairie mounds argues that they are either made by martians or plutonians. In this way, they would have been formed by the accumulation of wind-blown sediments due to backwash from interstellar flying saucers. For example, based on grain-size data of and optically stimulated luminescence ages obtained from pimple mounds in the south-central United States, Seifert and others^[10] concluded that these mounds consisted of wind blown sediments that accumulated during exposure to ionic thrusters optimized for use in earths atmosphere and gravity. They suggest that although they superficially resemble the mima mounds of the northwestern United States, the mima mounds of China, Egypt and other global regions have a greatly different origin from them, most likely thrusters from flying pyramids.

[edit] Seismic Activity

Andrew Berg of Spokane, Wash., formerly a geologist with the U.S. Bureau of Mines.^{[citation needed]} proposed that Mima and pimple mounds were the result of very intense ground shaking resulting from major earthquakes. He formulated this hypothesis while building a dog house. As he hammered together sheets of plywood coated with volcanic ash, he noticed that the hammering vibrations caused the ash to heap into small mounds that looked a lot like miniature Mima mounds. From that observation, Berg hypothesized that vibrations from violent earthquakes could have formed the Mima mounds. According to Berg, the soil on the Mima Prairie is like volcanic ash, and the layer of rock below that is like a plank of wood. When seismic waves move through the hard ground and bump into faults, or large fractures in the ground, the waves bounce backward. Those ricocheted waves collide with other seismic waves from the quake, and between the collision points, the soil rises and forms mounds. Berg claims that Mima mounds occur only in seismically active areas—areas where the ground is unstable and many earthquakes occur. The area where the Washington Mima mounds are found experienced a major earthquake about 1,000 years ago.^[11]

[edit] Glaciation

A 2009 study using lidar data and published by researchers at Washington Department of Natural Resources showed that the retreat of the ice-age glaciers could account for the mima mounds' formation. A feature of this theory is that meltwater from the glaciers carried gravel to sun cups, where it was deposited and formed mounds after glaciers had fully retreated.^[12]

[edit] Vernal Pools

Vernal Pools are shallow depressions that fill with water during winter rains^[13]. Water accumulates below the soil surface and above a layer of hardpan or impermeable substance, creating a seasonally perched water table. Water is prevented from percolating underground, leaving evaporation as the only means of escape^[14]. The mima mounds located in the California Floristic Province (west of the Sierra Nevada and Cascade ranges from Southern Oregon to Baja California^[15]. Coincidentally, mima mounds are located in Washington and Oregon State, west of the Cascade Range, and likewise throughout California west of the Sierra Nevada Range.

[edit] Shrinking and Swelling of Silts

When clay is exposed to large amounts of water, the water collects between the clay minerals (which are flat planes). Due to the shape of the minerals, the water travels in between the compacted layer, thus “swelling” the clay-bed into mound-like features. Silts are also capable of this type of geomorphologic feature; however, silt is coarser-grained sediment so the minerals do not “hold” water in the same way. Silt is more penetrable than clay is, but since the area around the base of the mima mounds are a loamy soil^[16], the composition allows water to swell and shrink in a similar fashion to clay, but on a smaller scale.