420 WILBUR C. KNIGHT 
commented on the Red Beds resting on the Archean south of 
the Union Pacific railroad, and also upon the conformable con- 
tact of the Red Beds and the limestones further northward. 
From my recent investigation I have found that the limestones 
shade almost imperceptibly into the red sandstones, and that the 
strata of the lower portion of the Red Beds are identical with 
the strata of limestones to the northward, the difference in the 
lithological characteristics being due to the varied physical con- 
ditions during sedimentation. Here is a very peculiar instance 
where rocks of the same age, and, in fact, identical strata, have 
been differentiated on purely lithological grounds. Just what 
proportion of the Red Beds will be equivalent to the limestones 
has not been determined; but probably not less than five 
hundred feet of the strata near the Colorado line will correspond 
to limestones and light-colored sandstones some fifteen or 
twenty miles to the northward, and possibly a greater thick- 
ness. 
From the data in hand it will be observed that physical con- 
ditions favoring the deposition of Red Beds had been in exist- 
ence for a long time prior to the forming of the fossiliferous 
band containing the Palaeozoic fossils. Above the fossiliferous 
horizon the formation is made up of the same, or similar, red 
sandstones and shales; but it is more uniform in color and per- 
sistent in its lithological characteristics, and to the northward 
these strata do not merge into limestones. On the other hand, 
the Red Beds are conformable throughout, and there is no line 
of demarkation discovered thus far that would act as a basis of 
subdivision. There are a few beds of gypsum and limestone, 
but these are not persistent enough to be utilized as boundary 
lines. For the above reasons I am in favor of placing the Red 
Beds in the Palzozoic. 
From a paleontological standpoint, likewise, it seems advis- 
able to refer the Red Beds to the Paleozoic. The fauna referred 
to is purely Paleozoic, and without the slightest evidence of 
Mesozoic types. It would be unreasonable to expect that a 
Mesozoic fauna could have developed from the one referred to 
