| 1. |
- Boelhouwers, J., Meiklejohn, I.
(author)
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Quaternary periglacial geomorphology of southern Africa : review and synthesis
- 2002
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In: South African Journal of Science. - 0038-2353 .- 1996-7489. ; 98:1/2, s. 47-55
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Journal article (peer-reviewed)abstract
- The literature on southern African Quaternary periglacial andglacial studies is qualitative in nature with an apparent lack ofscientific rigour. Landforms attributed to being of periglacial andglacial origin exist through a broad belt of high relief from theWestern Cape mountains along the Great Escarpment to theLesotho highlands. Present-day frost action is limited to thesurficial action of needle-ice and segregation ice resulting fromdiurnal to mild seasonal freeze–thaw cycles. Environmentalcontrols on current frost action are still poorly understood forthe Lesotho highlands, where frost-induced processes are animportant factor in accelerating land degradation. Relict periglaciallandforms are most reliably identified in the form of large patternedground, widespread solifluction mantles and blockstreams. Theseobservations are supported by adjunct information, which togetherindicate somewhat drier conditions than present. Erosional forms,such as nivation hollows, cirques, and cryoplanation terraces, lackpositive evidence and imply wetter conditions than at present.Interpretations suggesting rock glaciers, glacial cirques andformer ice wedges at low relative altitudes are highly anomalouswith respect to the other periglacial records and proxy data for theregion. The limitations of the current research literature suggestthat future emphasis should be directed towards sedimentaryrecords by means of clay mineral, soil micro-structural andchemical analysis and dating to improve the reliability and accuracyof the interpretations and their temporal framework
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| 2. |
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| 3. |
- Boelhouwers, Jan
(author)
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Quaternary slope development in the Lesotho Highlands: Review and alternative model
- 2003
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In: South African Journal of Science. - 0038-2353 .- 1996-7489. ; 99:1/2, s. 44-46
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Journal article (peer-reviewed)abstract
- Discusses the quaternary slope development in the Lesotho highlands. Nature and spatial distribution of quaternary slope deposits; Asymmetry in the quaternary sedimentary record of Lesotho highlands; Existence of perigalcial slope dynamics; Paleoenvironmental implications.
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| 4. |
- Nyberg-Berglund, Anna-Britt, et al.
(author)
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Genetic differentiation of a polyploid plant on ultramafic soils in Fennoscandia
- 2001
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In: South African Journal of Science. - 0038-2353 .- 1996-7489. ; 97:11-12, s. 533-535
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Journal article (peer-reviewed)abstract
- The most common and widespread alpine plants on ultramafic soils in Fennoscandia belong to the Cerastium alpinum complex (Caryophyllaceae). This complex consists of polyploid alpine plants, which show great morphological variation. Both hairy and glabrous morphotypes are found on ultramafic soils. To shed light on the evolution and the postglacial colonization of the C. alpinum complex, we have studied the genetic differentiation of populations on ultramafic soils in Fennoscandia. Thirteen populations in Norway, Sweden and Finland were analysed by starch gel enzyme electrophoresis. Preliminary results show that there is a genetic and geographical differentiation of populations on ultramafic soils, resulting in one eastern and one western group. This suggests that there were two independent postglacial colonization events of C. alpinum on ultramafic soils in Fennoscandia. The hairy and glabrous morphotypes are found both in the eastern and western population groups, suggesting that the morphotypes on ultramafic soils have a multiple origin.
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