(1) The John Day Basin lies between the north and
south ranges of the Blue Mountains, in north-central Oregon. It covers
an area of approximately 10,000 square miles and is drained by John Day
River and its tributaries. It has been the scene of great volcanic
activity, its rock masses being made up of numerous volcanic flows, with
alternations of ashes, tufas, sands, and gravels.
(2) No detailed geological study has been made of the
region, but contributions to this subject have been made by Le Conte,
Condon, Marsh, Cope, Wortman, Matthew, and Merriam, the most important
and comprehensive being by the latter author.
(3) Its fossil riches, in the shape of mammalian
teeth, were first brought to scientific attention in 1861. Since that
time an extensive vertebrate fauna has been described by Leidy, Cope,
Marsh, Wortman, Merriam, and others.
(4) The first fossil plants were found at Bridge
Creek in 1862, by Prof. Thomas Condon. Since that date collections of
plants have been made by Condon, Voy, Bendire, Merriam, Osmont, and
Knowlton. The plants have been studied and described by Newberry,
Lesquereux, and Knowlton.
(5) The fossil flora of the John Day Basin, as set
forth in the present paper, comprises 150 forms, distributed among 37
natural families and the anomalous group of Phyllites. Of the 150 forms
enumerated, 24 have not been named specifically, and 44 species and 1
variety are described as new to science. The previously known species
(6) The known fossil floras of the John Day Basin are
all of Tertiary age. The oldest, represented by the localities of
Cherry Creek, Currant Creek, and 3 miles above Clarnos Ferry, is
referred to the Lower Eocene. It is in the lower part of Merriam's
Clarno formation. The next younger in age, exposed at Bridge Creek,
1-1/2 miles east of Clarnos Ferry, one-half mile northeast of Fossil,
and Officer's ranch in the Butler Basin, occupies the upper part of the
Clarno formation and is Upper Eocene in age. The youngest plant-bearing
beds of the region, found at Van Horn's ranch and vicinity, are in the
basal portion of the Mascall formation. The age is regarded as Upper
(7) From the facts adduced in this bulletin it is
concluded that the conditions which prevailed in the John Day Basin
during Tertiary times extended also into central Washington,
northwestern Idaho, and western Oregon.