An associational study of Illinois sand prairie . excavation, normally orig-inating in the Panicum pubescens association by gradual ascendencyof the influence of wind,- resulting in increasing openness of theassociation. Blowouts sometimes start in the bunch-grass, usuallyby accident. Figure 10 (t>. 62) shows the beginning of a blowouton the slope of the dune to the left, A small bare expanse fromwhich the wind is gradually removing the sand is the first stageof the blowout. It gradually deepens, the sa,nd from the basin ofthe depression being deposited above the general level on the leesid
An associational study of Illinois sand prairie . excavation, normally orig-inating in the Panicum pubescens association by gradual ascendencyof the influence of wind,- resulting in increasing openness of theassociation. Blowouts sometimes start in the bunch-grass, usuallyby accident. Figure 10 (t>. 62) shows the beginning of a blowouton the slope of the dune to the left, A small bare expanse fromwhich the wind is gradually removing the sand is the first stageof the blowout. It gradually deepens, the sa,nd from the basin ofthe depression being deposited above the general level on the leeside. The deepening continues, the sides of the depression be-come steeper, except the lee slope, up which the sand is driftedand deposited as a low dune formation. The windward slope reachesthe critical angle, and from then the removal of the sand from thisside of the depression is by gravity. There are thus four phys-iographic divisions of the blowout, (1) the basin, from which sandis being removed by wind; (2) the windward slope, from which sand.
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Keywords: ., bookcentury1900, bookdecade1910, bookidassocia, booksubjecttheses
