243:), which are bounded on their periphery by joints and fractures, and, in sedimentary rocks, bedding planes above and below. Each Liesegang block consists of a relatively unaltered core surrounded by concentric, alternating shells of iron-poor (intermediate shells) and iron-rich ('iron' shells) composition which make up the Liesegang rings. These iron-poor and iron-rich shells follow the configuration of the outer shape of the block and are sub-parallel to its sides. The iron-rich and iron-poor shells vary in degree of cementation and, as a result, can produce
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these joints, the near-surface bedrock will be altered by weathering progressively inward along the faces of these blocks. The alteration by weathering of the bedrock will be greatest along the corners of each block, followed by the edges, and finally the faces of the cube. The differences in weathering rates between the corners, edges, and faces of a bedrock block will result in the formation of spheroidal layers of altered rock that surround an unaltered rounded
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and a corresponding increase in the volume of the altered rock. When the joints within bedrock form a 3-dimensional network, they subdivide it into separate blocks, often in the form of rough cubes or rectangular prisms that are bounded by these joints. Because water can penetrate the bedrock along
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has removed the layers of altered rock and other saprolite surrounding corestones that were produced by spheroidal weathering. This leaves many corestones as freestanding boulders on the ground's surface. Often the spheroidal weathering, which created these corestones and the enclosing saprolite
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weathering structures during subsequent erosion. The degree of development of
Liesegang rings as the result of weathering depends upon the spacing of the joint systems, groundwater flow, local topography, bedrock composition, and bed thickness.
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When saprolite is exposed by physical erosion, these concentric layers peel (spall) off as concentric shells much like the layers of a peeled onion. Within saprolite, spheroidal weathering often creates rounded
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Depending on local environmental conditions, spheroidal weathering of bedrock blocks defined by tectonically induced joints and fractures may result in the formation of prominent and well-defined
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occurred in the prehistoric past during periods of humid, even tropical climates. Frequently, the removal of the saprolite by erosion and exposure of corestones as freestanding residual boulders,
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in RW Fairbridge, ed., pp. 1041–1044, The
Encyclopedia of Geomorphology, Encyclopedia of Earth Sciences, vol. III. Reinhold Book Corporation, New York, New York.
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349:"Talus Caves: Geotourist Attractions Formed by Spheroidal and Exfoliation Weathering on Akure-Ado Inselbergs, Southwestern Nigeria"
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and results in the formation of concentric or spherical layers of highly decayed rock within weathered bedrock that is known as
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Spheroidal weathering is the result of chemical weathering of systematically jointed, massive rocks, including
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that were created by spherodial weathering and exposed by the removal of surrounding saprolite by erosion.
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478:, Department of Earth and Planetary Science, University of California at Berkeley, Berkeley, CA 94720
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Shahabpour, J. (1998) Liesegang blocks from sandstone beds of the Hojedk
Formation, Kerman, Iran.
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Granite
Landscapes of the World. (Geomorphological Landscapes of the World)
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Vulkanbomben, Wollsackverwitterung - interessante vulkanische
Strukturen
330:(5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp.
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within these blocks. These blocks typically consist of bedrock blocks (
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Alteration of
Sandstone as Revealed by Spheroidal Weathering.
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A.A. Balkema
Publishers Leiden, The Netherlands. 330 pp.
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Ethiopian
Journal of Environmental Studies and Management
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Neuendorf, KKE, JP Mehl Jr., and JA Jackson, eds. (2005)
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Form of chemical weathering that affects jointed bedrock
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212:-size core of relatively unaltered rock known as a
476:Featured Field Photo—Spheroidal weathering profile
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430:Oxford University Press Inc., New York. 384 pp.
391:Journal of Sedimentary Petrology. 49(3):901–909.
387:Heald, MT, TJ Hollingsworth and RM Smith (1979)
347:Kolawole, F.; Anifowose, A. Y. B. (2011-01-01).
34:Spheroidal or woolsack weathering in granite on
119:is a form of chemical weathering that affects
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405:Landforms and Geology of Granite Terrains.
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69:Woolsack weathering in sandstone at the
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50:Spheroidal weathering in granite,
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315:Causes of spheroidal weathering.
317:Earth-Science Reviews 7:127–141.
471:Images of Spheroidal Weathering
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101:Spheroidal weathering of a
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474:Swanson-Hysell, N. (2012)
183:rocks such as silicified
294:Spheroidal Weathering.
292:Fairbridge, RW (1968)
151:concentric weathering,
148:onion skin weathering,
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258:Exfoliation (geology)
154:spherical weathering,
117:Spheroidal weathering
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366:10.4314/ejesm.v4i3.1
158:woolsack weathering.
469:Mögen Sie Pflanzen?
328:Glossary of Geology
264:Exfoliating granite
112:, Western Australia
18:Woolsack weathering
163:Weathering process
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71:Externsteine
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181:sedimentary
138:, known as
492:Weathering
359:(3): 1–6.
275:References
197:serpentine
140:corestones
424:Migoń, P.
375:1998-0507
214:corestone
189:kaolinite
185:sandstone
129:saprolite
77:, Germany
42:, England
486:Category
313:(1971).
252:See also
245:box work
218:woolsack
205:chlorite
193:sericite
173:dolerite
144:woolsack
136:boulders
103:dolerite
56:A Coruña
40:Dartmoor
426:(2006)
225:erosion
210:boulder
169:granite
124:bedrock
121:jointed
110:Pilbara
73:rocks,
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203:, and
177:basalt
87:Musina
36:Haytor
432:ISBN
409:ISBN
371:ISSN
332:ISBN
230:tors
179:and
106:dyke
361:doi
216:or
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