336 C. W. HALL^KEWEENAWAN AREA OF EASTERN MINNESOTA 



of work accomplished. In- 

 deed, "the fundamental feat- 

 ure in the Icelandic eruptions 

 is the production of fissures 

 which reach the surface and 

 discharge streams of lava from 

 many points/' Such fissures 

 can be followed nearly 50 

 miles.* 



Dutton describes the Great 

 Hurricane fault of the Plateau 

 region, a fissure more than 200 



miles long, which is a 

 line of displacement 

 and volcanic activity.f 

 Dana X represents 

 tlie Hawaiian ishinds 

 as a group of centers of vol- 

 canic activit}' extending sev- 

 eral hundred miles beneath 

 the Pacific ocean. 



It would seem that the dis- 

 trict under investigation may 

 be compared with those men- 

 tioned by Geikie, Dutton, and 

 Dana in the geographical position of the 

 sources of suppl}^ and in the nature of 

 the force which ejected it. 



If, again, the question of time be taken 

 into consideration, it would seem that 

 with Strong |we must consider it a period 

 of deposition of detrital matter. This 



*Sir A. Geikie: Ancient Volcanoes of Great Britain, 

 vol. ii, 1897, p. 2G2. 



fC.E. Dutton: Tertiary history of the Grand Canyon 

 district. U.S. Geol. Survey, Monograph ii, The Hurri- 

 cane fault, pp. 112-n7. 



X Jas, D. Dana : Characteristics of Volcanoes, 1891, p. 2G, 



Figure :i.— Diagrammatic Sketch of Fault Line Vents frcym which Diabase possibly flowed. (After Geikie.) 



