OEDOVICIAN 32o 



with occasional oolitic bands. The beds are much checked up by joints 

 and frequently the bedding is not recognizable. At one point the beds 

 are much contorted and stand nearly vertical. The thickness of these 

 beds may be roughly estimated at not far from 600 feet. Their strati- 

 graphic relations to the Silurian beds were not determined. 



The character of the Ordovician fauna is shown by two lots of fossils 

 from localities in the Lower Eamparts. 



ORDOVICIAN FAUNA 



An Ordovician fauna was found at two localities in the bluish gray 

 limestones of the Lower Eamparts of the Porcupine. One of these is on 

 the north bank of the river, 1% miles above the Indian village, at 

 the lower end of the Eamparts. This fauna, although meager in the 

 number of both sj^ecies and individuals, clearly indicates an Ordovician 

 horizon. Mr E. 0. L'lrieh recognizes the following species in the fauna: 



Lichenaria sp. undet. Cameroceras sp. undet. 



Streptelasma (Petraia) ef. profun- GompJwceras sp. 



dum Conrad. Illwnus sp. 



Hormotoma near trentanensis U. & S. Biimastus cf. trentonensis Emmons. 

 Trochonema cf. umljUicatum Hall. 

 ilaclurea cf. nitida U. & S. 



Mr Ulrich considers this fauna to represent a Mohawkian or Middle 

 Ordovician horizon. 



Higher up the Porcupine, on the south side, about 6 miles above the 

 Indian village and three-fourths of a mile below some high cliffs on the 

 north side of the river, is a second occurrence of Ordovician fossils. The 

 following fauna was secured : 



Clitamionites sp. Maclurina manitoiensis Whitf. 



Poramhonites intercedens Pander ? Maclurina sulyrotunda Whitf. 



Lycophoria ? sp. Asaphiis 1 sp. 



The second fauna, like the first, occurs in a bluish gray limestone. 

 Some of the beds show an oolitic structure. In some places the original 

 bedding of the limestone is obliterated by innumerable joints. At one 

 point these beds stand vertical in the upper part of' the cliff, and are 

 variously contorted near the base. The Ordovician limestones seem 1o 

 be generally distinguishable from the Silurian by their gray or bluish 

 gray color and more magnesian character, the latter having generally a 

 buff color and a high percentage of magnesia. The complication of the 

 structure and the close interrelationship of the beds of -the two horizons 

 wroualit bv folding; and faulting make a close estimate of the thickness 



