KNowLToN.i PREVIOUS invp:stigation.s. 15 



collection coiLsisted of "reiiuiiii.s of inumnialia obtained by Mr. Condon from the 

 valley of Bridge Creek" (and "Big Bottom of John Day"), "a tributary of John 

 Day's Eiver, Oregon." The collection included new forms of Faracotylops {Mery- 

 cocharus), Rhinoceros, and Anchilhertmn. New occurrences of AgriocluiTUs, Leplo- 

 )neryx, Loplilodoti (?), Etollnrum, and a Dicotyles-like form were also noted. Most of 

 the previously known species, as identified by Leidy, were forms belonging to the 

 White River fauna, and he prol)ahly considered tlie John Day beds as of nearly the 

 same age as the White River. 



In 1873 Professor Marsh described " several new fossil mammals obtained by his 

 exploring party in the John Day country in 1871. He referred two forms to the 

 Miocene and one to the Pliocene, thus making the first statement regarding the age 

 of the beds. 



In his paper on the great lava flood of the West, Prof. Joseph Le Conte ^' makes 

 the first mention of the structural relations of the John Day formations. His state- 

 ment regarding the relation of the lava to the John Day beds is in i)art as follows: 

 "The lava of this region is * * * underlaid by the remarkable fo.ssiliferous 

 Miocene lake deposit of the John Day Valley; erosion has cut through the lava cap 

 into the soft strata beneath." 



The earliest general discussion of John Day geology which appears in literature is 

 the following statement i)ublished by Marsha in 1875: 



"The Blue Mountains formed the eastern and southern shores of this lake, but its 

 other limits are difficult to ascertain, as this whole country has since been deeply 

 buried by successive overflows of volcanic rock. It is only when the latter have 

 been washed away that the lake deposits can be examined. The discovery and first 

 explorations in this basin were made by Rev. Thomas Condon, the present State 

 geologist of Oregon. The typical localities of this Miocene basin are along the John 

 Day River, ami this name may very properly be used to designate the lake basin. 

 The strata in this basin are more or less inclined and of great thickness. One section 

 near the John Day River, examined by the writer in 1871 and again in 1873, seems 

 to indicate a thickness of not less than 5,000 feet. The upper beds alone of this 

 series correspond to the deposits in the White River Basin. The lower portion also 

 is clearly Miocene, as shown by its vertebrate fauna, which differs in many respects 

 from that above. Beneath these strata are seen, at a few localities, the Eocene beds 

 containing fossil plants mentioned above. They are more highly inclined than the 

 jNliocene beds, and some of them show that they have been subjected to heat. The 

 inferior strata elsewhere are Mesozoic and apparently Cretaceous. Above the Mio- 

 cene strata Pliocene beds are seen in a few places, but basalt covers nearly all." 



In this account we find the name "John Day" first used for the principal fossil 

 beds of the basin. The relation of this horizon to the great lava beds is also cor- 

 rectly stated, though it is not quite clear whether he considered the Pliocene as also 

 covered by the basalt flows. The Pliocene referred to is pretty certainly the Mascall 

 beds. It is known that Marsh camped near the typical exposure of this formation 

 and did some collecting in it. To what Marsh referred in his statements concerning 

 Eocene and Cretaceous it is not certain. He has, however, correctly described the 

 stratigraphic seqi;ence. 



In 1880 Prof. E. D. Cope'^ published the following statement concerning the geol- 

 ogy of the John Day country: 



"The regions of the John Day River and Blue Mountains furnish sections of the 

 formations of central Oregon. Above the Loup Fork or Upper Miocene there is a 

 lava outflow which has furnished the materials of a later lacustrine formation, 

 which contains many vegetable remains. The material is coarse and somewhat 

 gravelly and is found on the Columbia River, and I think also in the interior 

 ba.sin. Professor Condon, in his unpublished notes, calls this the Dalles group. 



a Am. Jour. Sci., 3d ser., Vol. V, 1873, p. -109. c Am. Jour. Set., 3d .ser.. Vol. IX, 1875, p. r,2. 



6 Am. Jour. Sci., 3d ser., Vol. VII, 1874, p. 167. dProc. Am. Philos. Soc, Vol. XIX, 1880, p. 61. 



