MESOZOIC ERA: THE AGE OF REPTILES 51 1 



extent and thickness were poured out ; dikes and sills were intruded ; 

 and in a few places volcanoes were in eruption. The evidence of this 

 igneous activity is especially well shown in the Connecticut valley 

 (Fig. 482), where in certain localities there are three distinct lava 

 flows. The lava forming the Palisades of the Hudson (Fig. 323, p. 326), 

 which varies in thickness from 300 to 850 feet and stretches for 70 

 miles from north to south, is an intrusion (Fig. 322, p. 326). The 

 faulting and subsequent erosion (Fig. 483) of the Triassic sediments 

 and lavas of Massachusetts, Connecticut, and New Jersey have re- 

 sulted in hills and mountains of (for these regions) unusual shape. 



Western Interior. — In the western interior of North America 

 (map, Fig. 480), the deposits are also for the most part red and, as 

 a rule, devoid of fossils. Some of the sediments were deposited in 

 fresh-water lakes, others in salt-water lakes, and some are probably 

 of eolian origin. 



Pacific Coast. — In the early part of the period, the Pacific 

 coast line, with the exception of a comparatively narrow bay that 

 stretched west from California to Wyoming, was probably farther 

 west than now. Later in the period the sea spread over the land 

 until it covered a large area in Alaska, Canada, British Columbia, 

 Washington, Oregon, Nevada, and California, and smaller areas in 

 Mexico. The fossils from the Triassic deposits of the west are in 

 many cases very abundant. 



Triassic in Other Continents. — Triassic rocks have a wide distri- 

 bution in Europe, where both marine and continental deposits occur; 

 the marine being, in general, in the south of Europe and the conti- 

 nental in the northern and central portions. The Triassic in Germany 

 has a threefold division (hence the name Triassic). The lowest con- 

 sists of deposits which were laid down in fresh and salt lakes, not unlike 

 those of the Triassic of the western interior of North America, and to 

 some extent are of eolian origin, as the dune structure of some of 

 the sandstone shows. Sun cracks, raindrop impressions, and tracks of 

 animals also occur. The relation between the fertility or barrenness 

 of a soil and the rock from which it was derived is well illustrated by 

 this formation in Germany. Since the rocks are composed of quartz 

 sand containing little plant food, the region underlain by them is not 

 cultivated, but has been allowed to remain forested, and hence this 

 formation has been called the " forest formation." 



During the Middle Triassic (Muschelkalk) an inland sea connected 

 with the ocean spread over a large part of the area of the earlier 



CLELAND GEOL. — 33 



