Dolomitic Glades of East-Central Missouri

Abstract

A characteristic feature of the landscape of the Ozarks is the occurrence on southand west-facing hillsides of barrens which are locally known as glades or cedar glades. Such glades, occurring on outcrops of thin-bedded dolomite or dolomitic limestone, principally of lower Ordovician age, have been studied in the area shown on the map (fig. 1). It includes about three-fourths of Jefferson County and small parts of adjacent Franklin, Washington and Ste. Genevieve Counties, Missouri, and lies from 25 to 50 miles west, southwest and south of the city of St. Louis, on the northeastern border of the Ozark Plateau. The unique character of the Ozark glades has long been recognized by botanists, though no extended accounts have been published. Discussions may be found in the papers on the Ozark flora by Palmer ('21) and by Steyermark ('34; '40), who consider them as relics of the former plains flora of the region. References to the glades may also be found in the geological and geographical literature (e. g., Weller and St. Clair, '28; Pike, '28; Sauer, '20; Cozzens, '37; '39). The present study is largely a by-product of two other investigations, by Brenner and by Erickson. Brenner 's interest in the glades grew out of his study of the environmental variables at the Gray Summit Arboretum of the Missouri Botanical Garden (Brenner, '42). Erickson is engaged in a study of the distribution of Clematis Fremonotii in Missouri, and the detailed mapping of the glades was done primarily as preliminary work for that study. Wraight became interested in the problem for its geographical and ecological implications. The analysis of the physical characteristics of the glades which follows is largely due to the field work of Brenner and Wraight. This paper is primarily descriptive, but an attempt has also been made to analyze the factors which are responsible for the occur-