THE 
AMERICAN GEOLOGIST. 
Vol. XXXIII. MARCH, 1904. No. 3. 
CONGLOMERATE DIKES IN SOUTHERN 
ARIZONA.* 
B^' Makil's R. Campbell, Washington, D. C. 
PLATKS IV-V. 
Until within the last ten or fifteen years few examples of 
clastic dikes had been recognized in this country and little was 
known regarding their origin. Recently through the publica- 
tions of Diller,t Cross,$ Crosby,§ Ransome,|| McCallie,^ New- 
som,** and others, dikes of this character are found to be of 
relatively common occurrence, especially in the west, and in 
some cases the source of the material and the mode of its ac- 
cumulation have been fairly well determined. In most cases 
the material is thought to have been forced up in an open or 
incipient fissure from some underlying bed, but in only a few 
cases has the existence of such a source of supply been demon- 
strated. 
During the past summer the writer had the opportunity of 
examining in southern Arizona some peculiar conglomerate 
dikes which are composed of material that can be correlated 
definitely with an underlying bed, and he takes this occasion 
• Published by permission of the Director of the V. S. Geological Surrey. 
tT-S. DiLLKR. "Sandstone Dikes'" Bull. Geol. Soc. Am., vol. i, 1890, pp. 
4.11-4-4-2. 
t Whitman Cross. "Intrusive Sandstone Dikes in Gianite," Bull. Gcol. 
Soc. .4/71.. vol. V, 189.3, pp. 225-230. 
S W. O. Crosby. "Sandstone Dikes accomp.nnying the Great Fault of Ute 
Pass, Colorado." Essca- Inst. Bull., vol. xxvii, 1897, pp. 113-14-7. 
II F. L. Ra.nsomr. "A Peculiar Clastic Dike near Ourav. Colorado, and Its 
.\ssociate Deposit of Silver Ore.," Trans. Am. Inst. Alin. Eng., vol. xxx. 1900, 
pp. 227-236. 
H S. . McCallik. "Sandstone Dikes near Columbus, Georgia," .\mer. 
Gbot,.. vol. xxxii. 1903. pp. 199-202. 
♦•J. F. .Yewsom. "Clastic Dikes." B II. Geol. Soc. .Am., vol. xiv, 1903, pp 
227-268. 
