deposited either before or after it. I had not time to go on with 
this interesting investigation or I should, without doubt, have 
been able to solve the whole problem of the relative ages of all 
the canyon rocks.” 
Again on page 42 he writes : 
“This valley (Junction Valley) is situated in one of the most 
interesting as well as one of the most beautiful regions in the 
park. The geologist might find a year’s profitable work within 
a radius of ten miles about Baronett’s Bridge, and the tourist 
could find almost unlimited sources of pleasure. Geographically 
there are illustrations of many most interesting problems of 
geological history and the very perplexing events of the volcanic 
Tertiary period may be studied to the best advantage. 
“North of the valley lies the range of Granitic Mountains that 
must have looked down in succession upon the Eocene, Miocene, 
and Pliocene lakes and witnessed the extraordinary events of the 
volcanic period. Here, during the latter part of the volcanic 
epoch, while the subaerial deposits were in process of formation, 
the erosion seems to have been more than usually deep. The 
trachytes and rhyolites were poured out into the valleys cut in 
the Tertiary and Paleozoic rocks. Subsequent flows filled in the 
valleys eroded from the first flows, and so on through the basaltic 
and conglomerate producing period. On account, however, of 
the occurrence of so many products together, their relations are 
hard to make out. This may be remarked of the Tertiary strata, 
especially the several groups of which cannot easily be distin- 
guished from the conglomerate formed in more recent times 
through alluvial and volcanic agencies, and possible identifications 
are very nearly impossible. Of course, prolonged study may make 
everything clear.” 
It seems remarkable to the authors of this paper that no 
attention has been paid to the penetrating observations of 
Holmes and his colleagues made over half a century ago. The 
report of 1878 is replete with careful observations and beauti- 
fully accurate drawings by this master artist of geological 
subjects and the scientific interpretation of scenery. We do 
not feel that it is necessary to quote the conclusions of all 
subsequent workers as the prevailing opinions regarding the 
geology and physiography of the Yellowstone Canyon appear 
to be expressed in the following paragraphs taken from J. P. 
Goode 2 and E. de Martonne 3 : 
2 Goode, J. P., The Piracy of the Yellowstone, Jour. Geol., 7, 261-271 
(citation, p. 261), 1899. 
