The formation is described in Geologic Formations of Eastern Oregon (1972) as follows: "The Mascall Formation consists of a maximum of 2,000 feet of fluvial sandstone, ash, light colored water-laid tuff, and well-rounded conglomerate. Within the Mascall Formation is a widespread ignimbrite unit which consists of 97 to 99 percent glass shards and minor amounts of anorthoclase, quartz, magnetite, zircon, and clinopyroxene."[2][3]
^Merriam, J. C., 1901. A contribution to the geology of the John Day Basin, Oregon: Univ. Calif., Dept. Geol. Sci. Bull., v. 2, p. 269-314.
^ abGeologic Formations of Eastern Oregon (East of longitude 121°30'), 1972. John D. Beaulieu. Bulletin 73. Oregon Department of Geology and Mineral Industries.
^Davenport, R. E., 1970. Geology of the Rattlesnake and older ignimbrites in the Paulina Basin and adjacent area, central Oregon: Oregon State University doctoral dissertation, 132 p., unpublished.
