THE PLIOCENE PERIOD. 311 



Wildcat, great thicknesses (4600 feet) have been assigned. Marine Plio- 

 cene beds are not known to have great development farther north, 

 but beds tentatively referred to this period occur up to elevations of 

 5000 feet in the St. Elias Alps. 1 It has been thought that Vancouver 

 and Queen Charlotte Islands were at this time connected with the 

 mainland. 



The fossils of the Pliocene beds of the Pacific Coast are said to 

 indicate a climate cooler than the present. 2 This may have been the 

 result of a broader connection than now between the Arctic and the 

 Pacific. 



Crustal Movements of the Pliocene. 3 



The tendency to crustal movement both by warping and by faulting, 

 which characterized the western part of the continent during the 

 earlier part of the Tertiary, seems to have continued at least inter- 

 mittently through the Pliocene, though the movements which took 

 place during the period are not always distinguishable from those of 

 earlier times, or from those which took place at its close. Deforming 

 movements often extend through long periods, and the Pliocene move- 

 ments were in many places probably no more than continuations of 

 movements begun in an earlier period, and continued into a later. 



About the close of the Pliocene there seem to have been wide- ,;: 

 spread crustal movements in most parts of North America. They 

 resulted in increased height of land, and the time of active erosion 

 which followed is sometimes known as the Ozarkian 4 or Sierran 5 

 period. In the east, the region overspread by the Lafayette formation 

 was somewhat higher than now, and in reaching this position, it was 

 perhaps somewhat deformed, though by no means all of the pecu- 

 liarities of topographic distribution (p. 302) are to be ascribed to defor- 

 mation, if the preceding explanation of the formation be correct. tVith 

 the elevation of the coastal plain, , the coast fine was probably shifted 



1 Russell, National Geol. Mag., Vol. Ill, pp. 171-2. 



2 Dall, op. cit., and the Messrs. Arnold, Jour, of Geol., Vol. X, p. 125, 

 3 LeConte, Jour. Sci., Vol. XXXII, p. 167, 1886, Bull. Geol. Soc. Am., Vol, II. 



p. 329, Jour, of Geol., Vol. VII, p. 546, 1899; Hershey, Science, Vol. Ill, p. 620, 1896; 

 McGee, 12th Ann. Rept. U. S. Geol. Surv. and Science, Vol. Ill, p. 796; also King, 

 op. cit., and Dutton, Mono. I, U. S. Geol. Surv. 



4 Hershey, Science, Vol. III. p. 620, 1896. 



s LeConte, Jour, of Geol., Vol. VII, p. 529. 



