SIXTH REPORT OF THE DIRECTOR I909 151 



miles south of Clinton, a 2 inch layer of green shale is locally 

 present a few feet above the basal green bed. Scattered throughout 

 the red shale are numerous green spots and after a shower the colors 

 are intensified so that the light green spots stand out in sharp con- 

 trast against the dull red matrix. The formation is everywhere 

 highly jointed and soon after exposure to the weather the rock 

 crumbles to a fine dust. The shale is very fine grained and, except 

 for color, it is remarkably uniform from top to bottom. So far 

 as observed it is entirely devoid of stratification planes. Thus it 

 is evident that depositio-n of the sediment must have occurred in 

 quiet water and under very uniform conditions. Except for cer- 

 tain organic patches below referred to, not a trace of a fossil has 

 been found in the formation near Clinton. At Syracuse the salt 

 bed rests upon the Vernon shale and the absence of fossils from 

 the shale is probably due to the fact that just before the real salt 

 pan conditions the water was too saline to permit much, if any, 

 animal life. 



Origin of color in the red shale. The red shale is very fine 

 grained, but examination of the powder or the thin section shows it 

 to be made up chiefly of tiny quartz grains which are imbedded in a 

 red matrix of earthy or claylike material. Occasionally small rhom- 

 bohedral crystals of some carbonate are noticeable. Because of the 

 opacity and softness of the shale thin sections are difficult to make 

 but it is evident that the color is not inherent in the quartz grains 

 which are themselves very clear and free from color. This is in 

 harmony with Russell's^ observations on the Newark sandstones, 

 that '' their color was not inherent in the particles composing them, 

 but was due to a fine, amorphous, claylike coating which enveloped 

 the grains and filled the intervening spaces." 



The red color is unquestionably due to the presence of de- 

 hydrated ferric oxid. On treating the red shale with hot hydro- 

 chloric acid the red color quickly disappears because the ferric oxid 

 dissolves and from the solution a good precipitate of brown ferric 

 hydrate is obtained by the addition of ammonia. Quantitative tests 

 by Dr A. P. Saunders of Hamilton College showed that a sample of 

 the red shale, treated with hot dilute sulfuric acid, contained 2.25^ 

 of ferric iron and .75^ of ferrous iron.^ The amount of ferric 



^ ot). cif. p. 44. 



^The amount of ferric iron here given is doubtless greater than is 

 actually present in the oxid form because the acid was boiled until it 

 became concentrated enough to effect a partial decomposition of the 

 green silicate residue below referred to. 



