578 EDWARD SAMPSON 



The jasper of this formation forms beds as much as 25 or 30 

 feet in thickness, though the zone through which these heavy beds 

 occur is probably not greater than 100 feet. However, at the 

 Southeast Arm of Fortune Harbor, where the Jasper is apparently 

 overlaid by several hundred feet of tuff, these tuffs contain many 

 thin beds of red and green chert a few inches in thickness. 



Good exposures are to be seen at the following places : the north 

 shore of Goldson Arm and the north shore of Indian Cove, both on 

 New World Island, and in several places in Fortune Harbor, 

 particularly at the two places where prospecting has been done on 

 the beds for their iron or manganese content. There is also exposed 

 on the trail from Round Harbor to Tilt Cove a very heavy bed of 

 jasper apparently in the same association as the others, but at this 

 place the very dense underbrush obscures the relations. 



Some of the occurrences of this type of chert contain radiolaria. 

 These will be described under the microscopic features. 



THIRD TYPE — THIN BEDS 



There remains one type to be described, the third type, which 

 occurs interbedded with a peculiar siliceous shale and often with 

 rhyoUtic tuffs. This type of chert is exposed at the following 

 places: the northern part of the western shore of Sansom Island; 

 between North Harbor Head and North Harbor on the Ship Run 

 of the Bay of Exploits; at Lawrence Harbor and also on the east 

 side of Winter Tickle, both on Ship Run; on the south side of 

 Leading Tickle, at and near the Ladle; and on the small islands 

 south of Gull Island in Badger Bay. 



These exposures have many features in common. The prevail- 

 ing type of chert is a green variety, having a porcelain-Hke texture 

 and a very perfect conchoidal fracture. In places thin beds of jasper 

 are of minor importance. The chert is usually interbedded with 

 tuffs. 



The individual beds of chert are thin, being rarely over a foot 

 thick, often from three to six inches thick, and in places less than 

 one inch thick. The thickness of individual beds is of great uni- 

 formity and the beds are persistent. In this respect, as in many 

 others, they resemble some of British radiolarian cherts of the same 



