Evidence of Quaternary glaciation in Southern Africa : moraines on the Bastervoetpad of the eastern Cape Drakensberg, South Africa

This volume of Quaternary International comprises the Abstracts from the XVth INQUA Congress held in Durban,South Africa, 3–11 August 1999

Multiresolution Approximation Using Shifted Splines

We consider the construction of least squares pyramids using shifted polynomial spline basis functions. We derive the pre- and post-filters as a function of the degree n and the shift parameter Δ. We show that the underlying projection operator is entirely specified by two transfer functions acting on the even and odd signal samples, respectively. We introduce a measure of shift-invariance and show that the most favorable configuration is obtained when the knots of the splines are centered with respect to the grid points (i.e., Δ=1/2 when n is odd, and Δ=0 when n is even). The worst case corresponds to the standard multiresolution setting where the spline spaces are nested

Centered Pyramids

Quadtree-like pyramids have the advantage of resulting in a multiresolution representation where each pyramid node has four unambiguous parents. Such a centered topology guarantees a clearly defined up-projection of labels. This concept has been successfully and extensively used in applications of contour detection, object recognition and segmentation. Unfortunately, the quadtree-like type of pyramid has poor approximation powers because of the employed piecewise-constant image model. This paper deals with the construction of improved centered image pyramids in terms of general approximation functions. The advantages of the centered topology such a symmetry, consistent boundary conditions and accurate up-projection of labels are combined with a more faithful image representation at coarser pyramid levels. We start by introducing a general framework for the design of least squares pyramids using the standard filtering and decimation tools. We give the most general explicit formulas for the computation of the filter coefficients by any (well behaving) approximation function in both the continuous $(L _{ \infty } )$ and the discrete $(l _{ \infty } )$ norm. We then define centered pyramids and provide the filter coefficients for odd spline approximation functions. Finally, we compare the centered pyramid to the ordinary one and highlight some applications

Fluvial conditions during the Holocene as evidenced by alluvial sediments from above Howison's Poort, near Grahamstown, South Africa

Mapping and analyses of alluvial sediments in the Berg River valley, near Grahamstown, has resulted in the identification of over 5 000 years of environmental stability in the early Holocene, in which flood plain sediments accumulated. Subsequent to 4390±90 BP environmental instability, probably due to climatic fluctuations, resulted in the formation of river terraces. Further research is needed to establish the area! limits of this sequence of Holocene climatic and environmental events

Partnership for success—community-based economic development: a case study of Ngolowindo Cooperative, Malawi

Africa has a disproportionate share of the world’s poorest countries and within this context economically weak states generally lack the ability to provide the ideal level of support and opportunities for their citizens. This paper examines how, in Malawi, a community-based economic development initiative, with the aid of a supportive NGO, has significantly improved rural livelihoods and facilitated market access in the formal market economy. Active government and NGO support for small scale irrigation farming coupled with their encouragement of community development led to the emergence of the Ngolowindo agricultural cooperative which serves as a useful model and example of locality-based development in Africa. After providing a context for the study in terms of both contextual literature and details specific to the Malawian context, the paper examines how the cooperative emerged, how it operates, what role the supporting NGO plays, and how products are sold. The study concludes with an overview of key findings and an examination of the lessons for local development in Africa.

Palaeoclimatic and archaeological implications of organic-rich sediments at Tiffindell Ski Resort, near Rhodes, Eastern Cape Province, South Africa

Analyses of organic-rich deposits from Tiffindell Ski Resort indicates that organic accumulation began somewhat before 4720 BP. This correlates well with the moister conditions known to have existed in the north eastern uplands of Eastern Cape Province (and in upland eastern Lesotho) in the later as compared with the earlier part of the Holocene. Palynological analyses of sediments dating from somewhat before 2790 BP to the present suggests that only limited environmental changes occurred in the pollen spectra. The wettest conditions apparently existed around 2700 BP, probably correlating with an increase in human occupation in the Eastern Cape (Southern) Drakensberg following the possible abandonment of that area during the dry phase(s) of preceding millennia