THE ACADIAN TRIASSIC 265 



removed by erosion or were never deposited there. The thicknesses 

 of the portions of the flows remaining between the waters of 

 St. Mary's Bay on one side and the Bay of Fundy on the other are 

 estimated as: 



Sandy Cove Tiverton 



Upper flow 30o±feet 150+ feet 



Lower flow 150^= 75+ 



On Grand Manan the section is quite similar to those given 

 above. The number of thin flows on the top of the series was not 

 counted accurately. The section is: 



Top. Ten(?) thin flows averaging 10-15 feet in 



thickness 100 feet 



Second flow 250 



Base. First flow 45° 



The number of flows exposed on Isle Haute is unknown. The 

 section at Cape d'Or consists of 5 flows, of which the lower one 

 (556 feet) is the thicker. At Cape Sharp and at Partridge Island 

 two flows appear to be shown. 



Only one petrographic description of the basalt of North 

 Mountain has been published. 1 On account of the similarity of 

 the basalts associated with the Newark group little attention has 

 been paid to those of the Acadian area. 



The basalt is a dark-gray or dark-greenish fine-grained rock 

 composed of plagioclase feldspar and augite with accessory amounts 

 of magnetite, olivine, and glass. The feldspar is a labradorite, 

 varying slightly in composition. The texture of the rock is ophitic, 

 laths of feldspar inclosing augites, or masses of augite inclosing 

 small feldspar laths. Chlorite, magnetite, limonite, hematite, 

 and serpentine are present as alteration products. 



The proportion of glass to crystalline matter, of labradorite 

 to augite, and the presence of olivine each depend on the proximity 

 of the section to the top or bottom of the flow. The top of the 

 flow is always quickly chilled in contact with the atmosphere, and 

 solidifies with a large amount of glass and a large number of gas 

 cavities. These cavities later become filled with quartz, calcite, 



1 V. F. Marsters, "Triassic Traps of Nova Scotia," Am. Geol., V (1890), 140-43- 



