376 DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



the Paradoxides zone and the pre-Cambrian. From the bottom of 

 the Paradoxides zone at Smith Point to the top of the Smith Point 

 limestone according to a calculation based upon a careful stadia 

 transit survey of the shore line (Fig. 43) there is a 'thickness of 546 

 feet. The total thickness in the number of limestone beds varies from 

 a few feet at Manuels to 100 -(- feet at Smith Point. The thickness 

 of the shales at Manuels below the Paradoxides zone is about 200 

 feet while the thickness of the shales at Smith Point within the corre- 

 sponding limits is over 400 feet, on the assumption that the Smith 

 Point limestone of Trinity Bay corresponds to that limestone of the 

 Manuels section which is just above the basal conglomerate. 



The increase in total thickness of the number of beds from the 

 east shore of Conception Bay to the west shore within the corre- 

 sponding limits would indicate a deeper portion of the Cambrian sea 

 when the sediments were being deposited. The fact that sediments 

 found below the Smith Point limestone on Trinity Bay are not repre- 

 sented at Manuels would indicate that sedimentation had been going 

 on for a longer time in the western portion of the basin than in the 

 eastern. Whether there actually was a greater amount of sedimenta- 

 tion in that portion of the basin remains to be investigated. 



As very little information is at hand with regard to the area of 

 the Cambrian rocks, it is quite out of the question for the writer to 

 attempt to outline the area once occupied by the Cambrian Sea in 

 southeastern Newfoundland. Moreover, it is likewise impossible for 

 the writer to outline the original manganese area as it looked in early 

 Cambrian times. If manganese occurs on the eastern shore of Pla- 

 centia Bay, as all descriptions of that occurrence seem to indicate, it 

 would seem that the original area of the manganese was approxi- 

 mately 200 or 300 square miles, assuming a more or less oblong shape 

 for the deposit. 



Although the basal conglomerate at Manuels is evidence of a defi- 

 nite shore line for the Cambrian sea at that part of the basin, there 

 is also evidence at the other localities examined, where, however, the 

 basal conglomerate is not found in any such large development. 

 There are littoral pre-Cambrian contacts at Topsail, Chapel Cove, 

 and Brigus ; all with typical shore deposits. 



