36 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



added to the waste. At times when the movements cease, the 

 cliffs wear back, the sediments become fine and may extend some- 

 what beyond the structural boundaries. At three different inter- 

 vals great floods of lava well out of fissures, spread far and wide, 

 and temporarily obliterate the life over large portions of the 

 basins. 



Now let the flight of time be slackened so that the succeeding 

 flashes of color which mark the change of seasons become distin- 

 guishable to the eye, and the work done in the successive seasons 

 may be perceived. From the vantage point of the marginal cliffs 

 the eye looks far through the dry air across an alluvial floor, now 

 shimmering in golden Triassic sunlight, now marbled with moon 

 and cloud. The eye looks far and sees island mountains partly 

 buried within the plains, but distance hides from view the farther 

 basin rim. During the season of heavy rains the loose waste is 

 washed from the upland borders over the alluvial pla'ins and into 

 the basin lakes and playas. An herbaceous vegetation, affording 

 food for a swarm of insect life and for the ruling host of biped 

 reptiles, springs into being with the coming of the rains. Then 

 the skies clear, the waters drain away, and during the following 

 season of dryness the landscape turns brown, save for the ever- 

 green trees and those smaller plants which grow near the scanty 

 permanent waters. The flood plains become dried and cracked, 

 sands blow from the temporary stream channels over the adjacent 

 flats, -and the warring horde of reptiles small and great leave 

 abundant bird-like footprints, as, impelled by thirst, they follow 

 the shrinking waters. The following layers of sediment seal for 

 future ages these records of a strange and varied life whose 

 story but for this would have been forever lost, since the alternate 

 drying and wetting of the sediments is a condition which prevents 

 the preservation of the bones. 



But, again looking toward the future and once more speeding 

 the flight of time, at last two or three miles of sediments are 

 seen to have accumulated in central Connecticut, and the Triassic 

 period has drawn to a close. 



Now, in the early Jurassic, an extensive crust movement is 

 inaugurated, but not as of old by folding or granitic injection and 

 metamorphism due to crushing forces. The progressive subsi- 

 dence of the basin with elevation of its walls which had marked 



