STUVER SERIES AND LISBURNE FORMATION 241 



No estimate can be formed of the thickness of the Stuver series, as its 

 lower limits are unknown. The exposed portion amounts to approx- 

 imately 2,000 feet. 



Age. — From its position below the the Lisburne series, which is con- 

 sidered to extend to below the middle Devonian, the Stuver series can 

 certainly not be younger than lower Devonian, and is regarded probably 

 pre-Devonian, to which it is provisionally referred. 



LISBURNE FORMATION {DEVONIAN) 



Character and occurrence. — The Lisburne formation consists of medium- 

 bedded limestones, with some shale. It occurs next above the Stuver 

 series, and. like the latter, has been greatly disturbed by crustal move- 

 ments. It forms a belt 15 or more miles in width, extending east and 

 west across the valley of the Anaktoovuk. On the southwest it is soon 

 delimited by the fault scarp of Contact creek, and farther westward by 

 the Carboniferous of the Fickett series, with which its relations are not 

 definitely known. To the eastward of the Anaktoovuk the belt seems 

 to widen. The series is probably in contact with the Carboniferous on 

 the south, while in descending the slope of the mountains on the north 

 it disappears beneath the mantle of glacial till, where, judging from 

 topography, it is probably soon met and overlain by the Mesozoic or 

 Lower Cretaceous. From what has been observed in the region of the 

 Anaktoovuk, the thickness of the formation is probably a little over 

 3,000 feet. 



Structure. — The entire area of the Lisburne formation here considered 

 is more or less deeply involved in the system of faulted and disturbed 

 blocks referred to under the Stuver series. At the north base of the 

 mountains west of the Anaktoovuk, the formation disappears beneath 

 the covering of glacial drift with a dip of 60 degrees to the north, while 

 east of the Anaktoovuk, a couple of miles distant, it similarly disap- 

 pears, but with a dip to the south at an angle of 75 degrees against the 

 fault scarp of the Stuver series, as shown in the section, plate 40. 



Age. — On the basis of Devonian fossils found in surface fragments near 

 the top of the mountains formed by the Lisburne formation, the latter 

 is provisionally referred to the Devonian. 



The Upper Devonian fossils thus collected by the writer have been 

 identified by Mr Schuchert as follows: 



Zaphrentis. Rhombopora. 



Aulocophyllum. JEridotrypa near or identical with E. 



Diphyphyllum. barrandei (Nicholson). 



Fenestella. Productella two species. 



Unilrypa ■ Spirifer disjunctus. 



Hemitrypa. Platyostoma. 



XXXVI— Bum,. Grot,. Soc. Am., Voi,. 13, 1901 



