Mima Mounds In The Kenya HighlandsMima Mounds are rarely reported outside the western United States. But Kenya has them, too. At elevations of 1500-3600 meters on Mt. Kenya, fields of mounds up to 6 meters in diameter and 1.5 meters high have been described. Cox and Gakahu have studied some of these African mounds and find them much like the North American Mima Mounds. They are found well above the range of the rhizomyid mole rat, a rodent similar to the North American pocket gopher in size and behavior. Quantitative measurements indicate the mounds to be constructed from dirt immediately surrounding the mounds. In short, the African mounds and probably those of North America seem to be the products of industrious rodents.
by William R. Corliss
Science Frontiers
No. 33: May-Jun 1984
(Cox, George W., and Gakahu, Christopher G.; "The Formation of Mima Mounds in the Kenya Highlands: A Test of the Dalquest-Scheffer Hypothesis," Journal of Mammalogy, 65:149, 1984.)Earthquakes And Mima MoundsIn a recent paper in Nature, P.B. Umbanhower et al described how they created regular geometric patterns in a layer of fine particles (only 0.15 mm in diameter) spread on a vibrating surface. At various forcing frequencies, they saw the layer of tiny brass spheres heap up into hexagonal honeycombs, circular piles, and even stranger shapes.
by William R. Corliss
Science Frontiers
No. 108: Nov-Dec 1996
(Umbanhower, Paul B., et al; "Localized Excitations in a Vertically Vibrated Granular Layer," Nature, 382: 793, 1996)
Comment. Nothing anomalous here, you say? Quite right, but perhaps there is in this experiment an explanation of a long-recognized geological anomaly: The origin of the famed Mima Mounds found scattered by the thousands in various regions of the planet, such as Mima Prairie near Puget Sound, in Washington State.
Actually, the demonstration of Umbanhower et al was preceded by a similar experiment back in 1990. In that year, A.W. Berg reported in Geology how he had covered a piece of plywood with a thin layer of fine sand (loess) and subjected the plywood sheet to impacts simulating earthquakes. Lo and behold, the sand rose up in an array of Mima Mound-like heaps. (See: SF#69 and p. 201 in the book Science Frontiers. This book is described here.
Umbanhower, a physicist, probably doesn't read Geology, but the results of his team's experiments certainly confirm Berg's simpler experiments and support the idea that quakes molded the Mima Mounds.
Many years ago I was a wilderness Ranger in the Rockies. I discovered a place where a creek ran through a narrow crevasse. There was a mini glacier there that formed an ice bridge across the creek. The cool thing was that in the summer, the creek thawed a high enough tunnel so a person could walk in. The roof looked like an inside-out golf ball, much like those mounds look. So i think there is a chance that melting glaciers may have had something to do with it.