62 NEW YORK STATE MUSEUM 



Appalachian gulf. Its glabella is large, rotund and coarsely pustulose, the 

 glabellar furrows obsolete, eyes large and the genal angles have minute 

 spinules. The pygidium is broad, the axis having six to eight well defined 

 rings, the first bearing a prominent tubercle, the pleurae having five to six 

 ribs all grooved and separated by deep furrows. These structural points 

 indicate an early period in the history of the genus, hence if Siluric, a final 

 stage. 



The construction of this assemblage as a whole as indicative of a very 

 late Upper Siluric marine fauna is justified and we would therefore put 

 together the entire mass of the strata 550 to 600 feet thick, as appertaining 

 to this horizon, that is the series of limestones and shales extending from 

 the reefs bordering the north flank of Mt Joli, southward almost to the 

 first palpable shear zone. 



Devonic — Perce massive. The attitude of Perce rock and of the 

 shore strata just described indicates a slight overturn of all. The older 

 strata uniformly lean up against those of younger age and we shall 

 presently note that this attitude implies that we are here dealing with 

 strata which are the northern limb of a heavy slightly overturned 

 anticline. 



Significance of its colors. The colors of the rock which are so striking 

 to the eye both in themselves and by contrast with the gray shore cliffs, are 

 dark purple-reds and light or gray yellows. The distribution of these tints 

 is in large measure in alternating or successive solid masses, but there is 

 besides this coloration an interesting modification into successive minor 

 bands of red along lines and cracks affording passage for bleaching waters. 

 The mass is coarsely veined with calcite and finely fractured and displaced 

 but these internal 'disturbances have not materially affected the continuity 

 or the attitude of the strata. The lesser color bands running in various 

 directions concentric to water passages are evidently of secondary origin 

 displaying the gradual reduction of the red iron oxid by the organic acids 

 m the percolating waters. The red bands are the residual and unbleached 

 remainder of the original solid color. 



