RT Journal Article SR Electronic T1 The validity of the so-called Wallala beds as a division of the California Cretaceous JF American Journal of Science JO Am J Sci FD American Journal of Science SP 473 OP 478 DO 10.2475/ajs.s3-45.270.473 VO s3-45 IS 270 A1 Harold Wellman Fairbanks YR 1893 UL http://www.ajsonline.org/content/s3-45/270/473.abstract AB