104 
THE GRAI^D OAJTON DISTRICT. 
though it is inferred that only a part and perhaps a small part of the Per- 
mian series is present while the lava cap has a thickness of 600 to 800 feet. 
Upon it stand a dozen basaltic cinder cones of comparatively recent origin, 
the largest and highest of which has received the name of Mount Emma 
The same name will be used to designate the platform upon which that 
crater stands. To appreciate the significance of these tabular masses it is 
necessary to look at the distribution of the lavas of the Uinkaret. 
BASALTS OF THE UINKARET. 
If we stand upon the summit of Mount Trumbull we shall observe, in 
every direction, a multitude of well-preserved basaltic craters. In the 
course of a few hours, with the aid of a large field-glass, it is possible to 
descry from this point between 120 and 130 distinct cinder-cones, and there 
are many others which will escape detection. Altogether there are between 
160 and 170 distinct vents upon the Uinkaret and its purlieus which have 
been observed and noted, and very likely some others have been overlooked. 
North of Trumbull the remotest one of the group is clearly defined at a dis- 
tance of about 26 miles. Southward a cluster of them stands upon the blink 
of the upper wall of the Grrand Canon 16 or 17 miles away, and there are 
others beyond concealed by the canon wall. Across the great chasm a few 
scattering ones may be seen nestled beneath the mighty southern palisade 
of the canon. Eastward of the Toroweap eight distinct cones appear upon 
the nearer part of the Kanab Plateau. But it is around the base of Trum- 
bull on all sides that they are huddled most closely together. In truth, they 
are so numerous in this vicinity that it is extremely difficult to count them, 
and we can never be sure that the counting is correct. None of these are 
of grand dimensions, and, in truth, most of them are very small. A few are 
of respectable size, attaining an altitude of 700 or 800 feet, and a diameter 
of a mile. Not one of them has yet been seen to contain any features of a 
novel character. They are all of the most ordinary structure, and ai'e as 
much alike among themselves as so many ant-hills. 
The grouping of the cones is not altogether capricious. The so-called 
