It. S. Lull — Life of the Connecticut Trias. 403 



One very characteristic physical phenomenon impressed 

 upon the sandstones and shales of the Connecticut valley is 

 that of mud-cracking as the fresh deposits dried under the 

 ardent heat of the Triassic sun. These cracks are often found 

 associated with the fossil footprints, and in many instances, 

 notably from the Portland, Connecticut, sandstone quarries, 

 they lie in the axes of the digital impressions, often radiating 

 from the tips of the toes, thus showing conclusively that the 

 drying was subsequent to the passage of the animal, the cracks 

 following the already weakened lines of least resistance. 



Yet another very characteristic Connecticut valley phenom- 

 enon is that to which the elder Hitchcock gave the poetic 

 name of "Nature's Hieroglyphics." As he says, the most 

 remarkable locality is at the Portland quarries, "where some- 

 times the surface looks like mosaic, or rather like a pavement 

 of polygonal masses, with mortar between the pieces." Bar- 

 rel! describes this as "mud-cracks filled with seolian sands." 

 He says (pp. 279-80) :— 



"Silt and sand will be blown over and till up the cracks 

 developed by the drying of argillaceous water-laid deposits. 

 Consequently, the sand is filled in under the raised rims of the 

 polygonal discs and becomes continuous with the mantle of 

 sand above. In this way the concavity upward of the indi- 

 vidual plates is preserved and the mud-cracks are not 

 obliterated, even in a silty clay which would crack and 

 crumble immediately upon being re wet by the advancing 

 waters of the following inundation. Experiments by the 

 writer [Barrell] go to show that the upturned edges of the 

 clay plates would not usually hold their form while the broad 

 sweep of sand-laden waters, should deposit clean sand both 

 under the edges and over the plates. The concavity of the 

 plates thus testifies to seolian burial and such may be distin- 

 guished from mud-cracked flats buried by fluvial action." 



Other phenomena indicative of climatic conditions are the 

 impressions of frequent hard showers, such as are often 

 observed in semi-arid regions, and pieces of recent sun-cracked 

 mud deeply pitted with rain impressions secured by Professor 

 Marsh on the Laramie plains in 1868 might well be of Triassic 

 origin. 



Still other phenomena, namely the impressions found in 

 Portland and attributed to a fucoid to which was given the 

 name of Dendrojphyeus triassicus by Newberry (1888, p. 82), 

 have been seen in actual formation upon the clay banks of 

 streams, and are nothing less than the wonderfully wrought- 

 out series of branching rill marks made by tiny streams of 

 trickling water. 



The animals of the Connecticut Trias, in so far as they 



