The local Distribution and Occurrence of the Fungi of Austin, 



Texas, and Vicinity 



By W. H. Long, Jr. 



To understand properly the peculiar fungal distribution and 

 occurrence of this vicinity it is necessary to state briefly the geo- 

 logical conditions and environment 



Austin is located on the Cretaceous, mainly on the Upper Cre- 

 taceous, and more specifically on the Austin-Dallas Chalk and 

 Shoal Creek limestone. As the name indicates, this formation is 

 marine and most of it deep-sea deposit. 



Our soil is therefore chiefly made from the detritus of these 

 old marine limestone strata. The surface here is very broken, 

 composed of rough, rocky hills with limestone exposed over the 

 greater part of them, with narrow, shallow valleys and arroyos, 

 whose soil has little depth, with here and there an occasional bed 

 of sand and gravel, the remnants of the Tertiary and Quaternary 

 river drift deposits. Austin is situated on the margin of the Ed- 

 wards Plateau, whose coastward border is the Balcones Escarp- 

 ment that extends from the northern line of Travis County to the 

 Rio Grande. 



The city proper being on the downthrow side of a series of 

 faults that determine this escarpment, is about five hundred feet 

 below the summit of the Edwards Plateau proper, and just east of 

 it and the Colorado River. Practically the same conditions pre- 

 vail here as on the plateau, viz. : rocky limestone hills, studded 

 with clumps of mountain cedar, barberry, mountain oak, and live 

 oak, none of which make a compact shady forest growth. 



While the valleys are sprinkled with a scattering growth of 

 mesquite, and near the edges of the creeks are found elm, hack- 

 berry and an occasional cottonwood, near the Colorado River, on 

 the Tertiary and Quaternary gravels, are found clumps of post 

 oaks and black jacks. 



Austin is also on the eastern margin of the Lower Sonoran 

 life zone, a zone characterized by a semi-arid xerophytic vegetation, 

 which corresponds well with the geological conditions. 



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