572 EDWARD SAMPSON 



The rocks of the region vary from Cambrian to Silurian age 

 and are, for the most part, of volcanic origin, pillow lavas being 

 abundant and developed to great perfection. The author believes 

 that widespread pillow lavas, such as are found in Notre Dame Bay, 

 are formed by subaqueous extrusion. 



There are three types of chert. The first is found in the inter- 

 stices of pillow lavas, the second as heavy beds of jasper found with 

 acid tuffs, and the third as thin beds interbedded with acid tuffs. 

 The bedded chert contains radiolaria but only as incidental fossils. 

 Cherts of these varieties have been described from many parts of 

 the world and some of the more important occurrences are cited. 

 The geologic occurrence in evQry instance presents features in 

 common with those of Notre Dame Bay. Particularly is this so 

 of the radiolarian cherts of Scotland. 



The silica of the cherts is thought to have been contributed to a 

 marine basin principally by magmatic emanations from submarine 

 vents or fissures. Processes are suggested by which precipitation 

 might have been brought about, the most important being the 

 precipitation of colloidal silica by the ions of sea water having 

 an opposite charge and, to a less degree, by oppositely charged 

 colloids formed by the interaction of magmatic and sea water. 



FIELD WORK 



This paper is a report on a portion of the field work carried out 

 by the Princeton University Geological Expeditions to Newfound- 

 land of the years 191 5, 1916 and 1919. Most of the work was of a 

 reconnaissance nature covering Notre Dame and White Bays. 

 In 1919 Notre Dame Bay was revisited and detailed work was done. 

 Though most of the work was on the copper mines, special attention 

 was given to the chert localities. 



ACKNOWLEDGMENTS 



It is a pleasure to make the following acknowledgments. Dr. 

 Arthur F. Buddington and Dr. WilHam M. Agar were both associ- 

 ated in part of the field work. They made the work possible and 

 have contributed much in discussion of the geology of the region. 

 Mr. Allan C. Brown and Mr. Hiram Blauvelt were each in the field 



