490 A. W. GRABAU PAI«BOZOIC DELTA DEPOSITS <:>F NORTH AMERICA 



show the rock to be exceedingly fine grained, consisting of tiny quartz 

 grains embedded in a red matrix of earthy or claylike material.^ 7 The 

 amount of ferric oxide is only 2.25 per cent and that of ferrous oxide 

 0.75 per cent, but it is so regularly disseminated that it produces a uni- 

 form coloring of the deposit. The green spots, often with black cent 

 are essentially free from ferric oxide, the analysis giving 1.19 per cent of 

 ferrous iron, which Miller believes is largely present in the form of car- 

 bonate. He holds that the presence of organic matter prevented the oxi- 

 dation of the iron in the spots and in the green shales above and below, 

 and thinks this organic matter may have been sea-weeds. This is at least 

 very doubtful, for no evidence of the neighborhood of the sea lias been 

 adduced. The Vernon suggests rather the accumulation of fine loess-like 

 material, chiefly as wind-blown dust. Such a dust may. of course, inclose 

 an abundance of organic substances, such as seeds and spores of land 

 plants, and even low forms of animal life which the wind may carry from 

 distant regions, and which when deposited will by their decomposition 

 locally prevent oxidation. 



In the Eochester region, where the Vernon shale has a thickness of 600 

 feet, it is separated from the Xiagaran series by the interesting Pittsford 

 shale, with its remarkable Eurypterid fauna. These deposits and their 

 contained Eurypterid fauna were described in detail by Sarle, 8S who gives 

 the following section in descending order ( page ,10 So > : 



Feet In. 



1. Red shale marlite « Vernon ■ 10 



2. Hard, fine-grained, yellowish dolomite, having an imperfect con- 



choidal fracture 2 



3. Red shale 1 



4. Break estimated at 3 



fk. Dolomite like number 2 3 



een shale or marlite 4 



7. Red shale 1 8 



& Break estimated at about 2 



Green shale 2 5 



10. Black shale, very fine texture, fossils, and with 1 inch dolomite 



parting i Eurypterid horizon i 1 6 



11. Green shale 1 



1 2. Dolomite like number 2 2 



13. Green shale or marlite 6 



14. Light colored water lime, some pyrites and sun cracks 



1 5. Bea green shaly marlite 7 



Total 51 7 



16. Impure yellowish porous limestone (Niagaran). 



H W. J. Miller : Origin of color in tire Vernon shale. N. Y. State Museum Bull. 14". 

 New York State Museum Bull. 69. 1903. pp. 1080-1108. plates 6-26. 



