268 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



in the sandstone profile, occur conglomerate strata, half an inch to an inch in thickness. In 

 these were found considerable remains of Coccosteus sp., Holoptychius sp., and Modolia angusta. 

 In the same strata with these were also seen indeterminable plant fossils. Slightly higher up 

 in the profile, however, in a black shale which occurred in two lentiform masses, 18 inches and 

 6 feet in thickness, were found numerous plant fossils. 



Prof. Nathorst, of Stockholm, who has kindly undertaken the examination of these, says 

 that among others are ArcJiosopteris fissilis Schmalh. and Arch, archetypus Schmalh., both 

 characteristic of Upper Devonian. In examining the material collected. Prof. Nathorst also 

 found with the plant remains some remains of fishes. 



LoWj^^"® who quotes the foregoing description from Schei, comments on it as 



follows : 



From the above it wUl be seen that on the southern side of EUesmere there is a complete 

 succession of strata, bearing fossils from Middle Silurian age up to the Upper Devonian. These 

 strata have an aggregate thickness of 8,000 feet and form the thickest and most carefully 

 measured section of the Silurian and Devonian beds of the Arctics. 



The southern shore of Jones Sound presents a different section, which is thus 

 described by Low: ^®" 



On the southern and southwestern parts of North Devon the Silurian strata are much 

 thinner than those described by Schei. At Cuming Creek the Archean gneisses were found 

 overlain unconformably by red and purple arenaceous shales and thin-bedded sandstones 

 having an aggregate thickness of 50 to 100 feet. These in turn were succeeded by beds of 

 impure limestone of light-gray or creamy color. The beds are usually under 2 feet in thickness 

 and separated by thinner beds containing a considerable amount of clay. These light-colored 

 limestones have a thickness of over 1,000 feet in the cliffs on both sides of the creek. The 

 sides of the cliffs are covered with broken limestone, so that it was impossible to measure a 

 section up them, but in two or three places a darker-colored limestone conglomerate was found, 

 made up of small pebbles cemented by a dark shaly matrix. Fossils are only found in the beds 

 immediately overlying the dark shales and sandstones of the base. These show that the lower, 

 limestone is of Silurian age, about the horizon of the Niagara. 



Similar conditions prevail in the cliffs at Beechey Island, where a large collection of fos- 

 sils was obtained from the lower limestone beds, while others, picked up loose but evidently 

 fallen from the cliffs above, showed that the upper beds passed close to if not into the Devonian. 



Similar Silurian limestones constitute the island of Cornwallis, to the westward of North 

 Devon, while in the remaining Parry Islands farther west the Silurian strata are lost beneath 

 the Devonian and Carboniferous rocks of those islands. 



