THE ACADIAN TRIASSIC 



21 



shore by a low, swampy area which is 

 covered by the sea at very high tides. 

 On the northwest is Gilbert's Cliff, rising 

 to a height of 60 feet, and on the northeast 

 Parrsboro Pier (Fig. 13). 



The basalt on Partridge Island (Fig. 14) 

 is partly columnar and partly vesicular. It 

 probably consists of two flows. Stilbite is 

 very abundant in geodes in the amygdaloid. 

 At the base of the lower flow the highly 

 weathered amygdaloid is 15 feet thick. 



The Triassic shales and sandstones are 

 seen underlying the basalt on the west 

 side of the island, dipping southward at an 

 angle of 10 to 35 degrees. Near Gilbert's 

 Cliff are red clays of Recent age, overlying 

 the beveled, upturned edges of the ripple- 

 marked Pennsylvania shales. The Triassic 

 is not exposed to show whether this surface 

 was the one on which the Triassic was 

 deposited or whether it was the one made 

 by the Pleistocene ice-sheet. 



Greenhill-Five Islands. — From a point 

 3 miles east of Parrsboro, near Greenhill, to 

 Five Islands, there is an almost continuous 

 strip of Triassic, faulted down against the 

 Riversdale-Union series of Pennsylvanian 

 age (Fig. 15). The entire region has suffered 

 extensive faulting and, with these move- 

 ments, gypsum veins have been introduced. 



The Newark comprises red sandstones 

 and some shales, with occasional beds of 

 green sandstone or shale; tuff and ag- 

 glomerate beds ; and basalt flows. The dis- 

 tribution of these rocks is very irregular, 

 owing to the faulting, and is disturbed by 

 extensive landslides in the volcanics. 



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