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Malde, 1964). in the Present Status of North Texas 10,000 Years Ago (Kupsch, 1960)

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Malde, 1964). in the Present Status of North Texas 10,000 Years Ago (Kupsch, 1960) Ritchie, 1953; Malde, 1964). In the Present Status of North Texas 10,000 years ago (Kupsch, 1960). The Central Valley of California, along the Origin Theories retreat was followed by a warming base of the Sierra Nevada Mountains, trend which lasted from about 8,000 Although a myriad of hypotheses the Hydrostatic Pressure Theory is B.C.to the beginning of the Christian have been projected concerning mima popular (Nikiforoff, 1941; Retzer, era (Dix, 1964) and is recognized as mounds in north Texas, no specific 1945). A recent study of landscape the Hypsithermal period (Deevy and theory of mima mound formation is features of the Texas Gulf Coast by Flint, 1957). During the Hypsithermal commonly accepted.’ Theories of Aronow (1968) resulted in a theory of period, the deciduous forest retreated erosion and accumulation are “Landscape Deterioration.” eastward and grasslands occupied the currently the most widely accepted. The Patterned Ground Theory is vacated area. Some members of the The erosional theory suggests that the based on the concept that a network forest flora, especially grasses, removal of the intermound area by of polygonal-fissured ice could have withstood the climatic change. These running water and wind has left the developed on the landscape early in species survived, reproduced, and mounds as essentially residual forms the last ice recession. As the landscape integrated with the grassland flora (Featherman, 1872; Holland et al., began to thaw, the meltwater removed (Dix, 1964). Gleason (1923) noted 1952; Goebel, 1971). Goebel (1971) the glacial till from around the still that the three most important grass postulated that mima mounds in north frozen hemispheroidal cores of each genera Texas primarily result from a low (Andropogon, Sorghas trum, polygon. When these cores melted and in the Illinois Tall-Grass stream-base profile and the low angle Panicum) they formed the mima mounds. of regional dip. However, Cain (1974) Prairie, plus Sporobolus to the south, The Hydrostatic Pressure Theory is belong to this group. There has been discounted strike and dip factors in a based on observations made while some question concerning the similar location because they are studying the soil profiles of the horizontal. Cain also points out that Hypsithermal (forest-retreat) influence mounds and intermound areas. on the vegetation of Texas (Graham mima mound spacing is not random “Holes” were observed to occur in the and Heimsch, 1960), but, if any area and, therefore, cannot result from rill hardpan where it passed beneath the of Texas was affected, it would have erosion around chance nuclei. mounds. It was theorized that the been the northern portion of the Vegetation is not characteristically hardpan predated the mounds, and Blackland Prairie. randomly dispersed (Greig-Smith, that hydrostatic pressure of 1964). Dominant species on the groundwater descending from steep The Accumulational Theory Sporobolus-Tridens-Paspalum slopes of the high Sierras into the community type have been identified (Olmstead, 1963; Cain, 1974) pro- relatively flat plain of the Central with wooded or mesic situations jected the concept that bunch grasses, Valley forced the groundwater up (Hitchcock, 1950; Launchbaugh, small shrubs or trees served as centers through the “holes” in the hardpan. 1955). It is quite possible that these of accumulation of wind-blown soil As water seeped upward, it carried species, or their ancestors, developed and silt. Bailey (1892) discounted subsoil material which formed the as dominants following the forest most other theories for mima mound mounds. This could have happened formation in the Blackland Prairie: retreat to the south and east. during final deglaciation in the forest-retreat origin of the “all are on rolling land and not flood A mount ains, when meltwater was vegetation would seem to support the land. They are clay soil [sic] 2 so plentiful. A c cumulational Theory of mima cannot be dunes.. Are too The Landscape Deterioration numerous for human work, too large mound formation. This theory is Theory offers an explanation for the for animal mounds, unless made by founded on the belief that, once the formation of pimple mounds on the surface horizon(s) had. developed, the Megatherium. Are too circular and Coastal Plain. Mounds are restricted in even for iceberg or glacier deposits.” climate of the area became arid and this region to Pleistocene and possibly vegetation became discontinuous. early Recent surfaces with slopes less Deflation of the surface soil occurred than 10 feet per mile. They occur on New Support for the on the barren areas and accumulated relict fluviatile deposits (especially Accumulating Theory around clumps of remaining levee and point bar), barrier islands, vegetation. When humid conditions The Sporobolus-Tridens-Paspalum and anomalously lagoonal deposits. In returned, a new profile formed community type covers the portion of this region mima mounds gradually between the mounds. The erosional the Blackland Prairie of Texas where disappear with time. periods may have been during the arid mima mounds are common (Collins, period which caused the forest to Mima mound origin has been 1972). The prominence of Sporobolus retreat eastward, since wind erosion is attributed to gopher (Geomys or silueanus on this community type may Thomomys) activity in Washington offer insight to the origin of the prevalent in arid situations (Holland et (Dalaquest and Scheffer, 1942), mounds. al., 1952). This conclusion is in California (Arkley and Brown, 1954), The last ice sheet retreated from agreement with findings of Cain and Minnesota (Ross et al., 1968). The the northern fringe of the area now (1974). After extensive study, he gopher theory may be succinctly recognized as the North American postulated that mima mounds in stated by asking which came first, the Midcontinental Grasslands about southwestern Louisiana were the result gopher or the mound. However, it is of erosional action depositing material difficult to imagine gophers producing ’ Personal communication from Saul at the base of trees. Instead of 4O,OOO,OOO mima mounds (Cain, Aronow (1974). Hypsithermal period influence, Cain 1974). 2 Emphasis by author. suggests the gran seco catastrophe of 210 JOURNAL OF RANGE MANAGEMENT 28(3), May 1975 Darwin (1845). He correlates mound Dalaquest, W. W., and V. B. Scheffer. 1942. Holland, W. C., L. W. Hough, and G. S. Murray. 1952. Geology of Beauregard alignment and regular spacing to a The origin of the mima mounds of western Washington. J. Geol. 50:68-84. and Allen Parishes. La. Geo. Surv., Geo. vegetational-erosional origin. Darwin, C. 1845. The voyage of the Beagle. Bull. No. 27. Present day examples of p. 137-139, 491-492. Murray, London. Krinitzsky, E. L. 1949. Origin of pimple vegetation-erosional mound origin are Deevy, E. S., and R. F. Flint. 1957. mounds. Amer. J. Sci. 247:706-714. found in Coppice Dunes and Rotura Postglacial Hypsithermal interval. Kupsch, W. 0. 1960. Radiocarbon - dated Science 157:182-184. organic sediment near Herbert, Soil near Las Cruces, New Mexico Dix, R. L. 1964. A history of biotic and Saskatchewan. Amer. Geog. Sot. Spec. (Gile, 1966; 1967). The mima mounds climatic changes within the North Pub. 36. of northeast Texas may well have had American grassland. In V. R. Crisp, ed. Launchbaugh, J. R. 1955. Vegetational a similar origin. Grazing in terrestrial and marine changes in the San Antonio Prairie. Ecol. environments. Blackwell Sci. Publ., Monogr. 25 :39-57. London. Malde, H. W. 1964. Patterned ground in the Literature Cited Featherman, A. 1872. Third annual report Western Snake River Plain Idaho, and its Allgood, F. P., and F. Gray. 1973. Genesis, of botanical survey of Southeast and possible cold-climate origin. Geol. Sot. morphology and classification of Northwest Louisiana. 5:192-195. Amer. BulI. 75:191-200. mounded soils in eastern Oklahoma. Soil Gile, L. H. 1966. Coppice dunes and the Nikiforoff, C. C. 1941. Hardpan and Sci. Sot. Amer. Proc. 37:741-753. Rotura soil. Soil Sci. Sot. Amer. Proc. microrelief in certain soil complexes of Arkley, R. J., and H. C. Brown. 1954. The 30:657-660. California. U.S. Dep. Agr., Tech. Bull origin of mima mound (Hogwallow) 745. Gile, L. H. 1967. Soils of an ancient basin microrelief in the far western states. Soil Newcomb, R. E. 1952. Origin of mima floor near Las Cruces, New Mexico. Soil Sci. Sot. Amer. 18:195-199. mounds, Thurston County region, Sci. 103 1265-276. Aro now, Saul. 1968. Landscape Washington. J. Geol. 60:461472. deterioration and the origin of pimple Gleason, H. A. 1923. The vegetational Olmstead, R. K. 1963. Silt mounds of mounds: Summary of unpublished paper history of the Middle West. Ann. Ass. Missoula flood surfaces. Geol. Sot. presented to the Soil Survey Technical Amer. Geog. 12:39-85. Amer. Bull. 74:47-54. Work-Planning Conference, Texas A&M Goebel, Joseph E. 1971. Genesis of PdwB, T. L. 1948. Origin of the mima Univ. Microknoll topography in Northeast mounds. Sci. Monogr. 66:293-296. Bailey, V. 1892. Field notes of Vernon Texas. Unpublished MS Thesis, East Retzer, J. L. 1945. Morphology and origin Bailey in Texas, 1892. Copied by W. B. Texas State Univ., Commerce. of some California mounds. Soil Sci. Davis. Special Collections Library, Texas Graham, A., and C. Heimsch. 1960. Pollen Sot. Amer. Proc. 10:360-367. A&M Univ., College Station. studies of some Texas peat deposits. Ritchie, A. M. 1953. The erosional origin of Cain, R. H. 1974. Pimple mounds: A new Ecology 41:751-763. the mima mounds of Southwest viewpoint. Ecology. 55:178-182. GreigSmith, P. 1964. Quantitative plant Washington. J. Geol. 61:41-50. Collins, 0. B. 1972. Climax vegetation and ecology. Butterworths. London. Ross, B. A., J. R. Tester, and W. J. soils of the Blackland Prairie of Texas. Hitchcock, A. A. 1950. Manual of grasses of Breckenridge.
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