LOWER CAMBRIAN TERRANE 3O9 



Feet. 

 2h. Reddish-purple, argillaceous shales, with irregularly dis- 

 tributed bands of nodular limestone of varying thickness. 

 A layer of nodular limestone 42 feet from the summit 

 has 12 inches of pinkish and reddish-purple limestone 

 above, with 10 inches of greenish limestone below. In 

 both layers numerous tubes of Coleololdes occur. At 

 66 feet below the summit a second band of nodular 

 limestone 20 inches in thickness occurs. Thin layers 

 of nodular limestone occur both above and below the 



two thicker bands mentioned 136 



2i. Green argillaceous shale, with a few thin layers of purple 

 shale, also scattered layers of pinkish-colored, nodular 



limestone TpVi 



Fossils : 



Annelid trails are abundant in some portions of the 

 greenish-colored shales. 

 2j. Reddish-purple shale, with payers of greenish- and pinkish- 

 colored limestone nodules scattered irregularly on the 

 line of bedding. The nodular limestones are usually 

 from 2 to 4 inches in thickness, but at 60 feet from the 



top a layer 12 inches thick occurs 185 



The section is here cut off by the drift coming down to the 

 water's edge. 

 The nodular limestones of the Smith Point section are one of the 

 most noticeable features of the lower portion of the section. Plate 

 XXII illustrates narrow bands of nodules about 350 feet below the 

 massive nodular limestone of Smith Point, which is beautifully shown on 

 plates XXIII and XXIV. The only fossils found in the lower part of the 

 section except annelid trails occur in the nodules. The bedding planes 

 of the shale in the slate quarries on Smith Sound are clearly indicated, 

 at nearly right angles to the cleavage, by the lines of scars left by the 

 nodules, as is shown by plate XXV. 



Base of Cambrian in Smith and Random. Sounds. — The 

 base of the Cambrian is exposed at the slate quarries east of 

 Tilton Head, on the north side of Smith Sound, in the synclinal 

 basin formed of the Avalon and subjacent Cambrian rocks. 

 The section, however, is not here complete. On the south 

 side of Smith Sound, near Britannia Cove, the Smith Point 

 limestone, carrying H3'olithes, etc., is well exposed, and 220 

 feet above it, in the green shales, Olenellus (//.) broggeri 

 was found. Below, the limestone beds are much broken. 

 Crossing Random Island from Britannia Cove to the north shore 

 of Random Sound, one finds a much more complete section, ^ 



