Blum Rockshelter, an archeological site near Blum in Hill County, was discovered by George Benson in 1951. Because it was to be covered by the flood-control pool of Lake Whitney, it was excavated in 1952 by Edward B. Jelks as part of a salvage program to save archeological evidence in danger of being destroyed. The rockshelter was formed as Nolan's River cut into a soft limestone bank. Eventually the course of the river shifted slightly to the east, leaving a shelter on the west bank. During floods the river deposited sediments on the floor of the shelter, thus producing a stratigraphic separation of the artifacts left there. Several chipped stone knives, scrapers, drills, and arrow points were found, as well as some bone tools and a few Caddoan-style pottery fragments. Excavation of these artifacts provided the first evidence of a clear temporal separation between two divisions of the Central Texas Aspect. Scallorn-type arrow points, which are a defining feature of the Austin Focus, were found mainly in the lower levels of the excavation. Perdiz-type points, diagnostic of the Toyah Focus, were found only in the upper levels. This suggested that the Toyah Focus was the later of the two divisions and possibly developed out of the Austin Focus. The chronology was corroborated by a substantially larger sample of artifacts subsequently found at the Kyle Rockshelter. The artifacts and field notes from Blum are stored at the Texas Archeological Research Laboratory, J. J. Pickle Research Center, University of Texas at Austin.