•22 MKSOZOIC FLORAS OF L'XrrED STATES. 



lower Littlo Colorado \'allev (here occur numerous somewhat calcareous 

 (•lav lenses, th(> Vuur takino; the form of brijiht white stripes, while the 

 chiv is usually purple or pink. These are wry distinct objects and 

 vary in size from lenses 10 oi' even 20 feet in lenjith to small lenticular 

 blocks or someuliat o\;il or even spherical cla\' balls oi' pellets. These 

 calcareous clay inclusions are scarcely seen faiihei- to the southeast, 

 ]>ut on Red Butte they are well marked, and hei'c the clay becomes 

 l)rillianl red and constilules a true paint stone. Another fact to l)e 

 noted in connection with ttie Lithodendron beds is that at certain local- 

 ities, notably on Hed l^utte, there is at its base a clear indication of a 

 transition to the Moencojiie formation. The cono:lomerates proper are 

 underlain ))>' arjiillaceous shales closely resembling those of the I\Ioen- 

 copie, l)ut beneath these is a sandstone ledge which can not be referred 

 to the lower ch vision, as it is more or less cross-bedded, possesses con- 

 siderable grit, and has included in it small clay pellets similar to those 

 of tlie true conglomei'ate series, in which I have for this reason included 

 it. This condition of things may be somewhat puzzling from the strati- 

 graphical point of view, but the disadvantage in this respect is much 

 more than compensated for by the evidence that it furnishes in fa\'oi- 

 of the view that all of these beds really constitute one great series, 

 and as opposed to the view which it may l)e inferred that certain geolo- 

 gists hold that the series of these beds which I have included under 

 the name of Moencopie belongs to a different system and is in some 

 way connected with the underlying Paleozoic rocks. This view, in the 

 light of the al)Ove-mentioned facts, is, in my opinion, quite untenable. 



THE LEKOUX MEMBER. 



Under the name Leroux I include the remainder of the Shinarump, 

 deriving the name from Leroux Wash," which enters the Colorado 

 Valley 2 miles l)elow Holbrook, and on which, some 15 miles north of 

 Ilolbrook, this member attains the greatest development that I have 

 obsei-ved, probably I'eaching its maximum of 800 feet. These beds, 

 too, if stvuUed at localities where they are less developed, might be sup- 



"The name "Leroux's fork" was given to this wasli by Lieutenant Wliipplc's pnriy. wlid fdllowed it 

 down some di-stancc and enoiimpcd at its jiincfion with tlie Little Coloiiulo on Dccciiilx'i .'), 1S.53, this Ix'ing 

 their Camp 79. See Pacific Railroad Reports, Vol. UL Ft. I, p. 7.5. The name is written in two words on 

 the Ijiitid Office map of Arizona. 



