I9I4.] CONCEPTION AND TRINITY BAYS, NEWFOUNDLAND. 385 



5 feet above the limestone there are thin seams full of comminuted 

 fragments of small Lingiilella, and HyoUthes shells. The upper part 

 of this shale is conspicuous because of the conchoidal fracture with 

 which it breaks and the presence of local aggregations of small sub- 

 spherical black nodules some of which show pinkish centers of some 

 fine-grained' minerals such as rhodochrosite or manganiferous cal- 

 cite. MnOo occurs as small dots or as dendritic areas on the frac- 

 ture planes. Microscopically, this is a chloritic micaceous shale con- 

 taining sparingly, among the visible minerals, irregular grains of 

 plagioclase, quartz, pyrite, magnetite and limonite in descending 

 order of abundance. 



219 A 2 is a nodular shale bed of .5 of a foot in thickness and 

 forming the sloping surface over which the stream runs. This bed 

 is noteworthy because of the Cryptozoon colonies showing on the 

 surface (see Fig. 10). 



219 A 2a, the lower portion of this bed, is a green shale contain- 

 ing frequent small subspherical nodules and disseminations of a pink 

 carbonate which effervesces freely and is in all probability a man- 

 ganiferous calcite similar to the pink nodules analyzed (see page 395) . 



219 A 2b is the Cryptozoon shale bed and contains roughly con- 

 centric or zonal structures measuring i^ inches in diameter, irreg- 

 ular and sub-spherical nodules measuring i inch in diameter, and 

 intercalated lenses of manganiferous calcite. These nodular and 

 Cryptozoon structures weather brown. Scattered through the bed, 

 particularly the shaly portions, are blades of barite. 



Alicroscopic examination of this Cryptozoon bed brings out noth- 

 ing which can be said to be of an organic structure. What struc- 

 ture there is may be characterized as broken veinous, concentric and 

 laminated. The texture in great part is crystalline. The greater 

 portion of one of the nodules consists of calcite and carbonate. Bar- 

 ite occurring as long blades is determined principally by the two 

 cleavages, c and m, its birefringence greater than quartz and its 

 biaxial -j- character. Chlorite either alone or in combination with 

 carbonate is found replacing barite. Calcite or carbonate occur as 

 irregular masses or as rudely formed or incipient spherules. Hema- 

 tite occurs in the banded portions as more or less massive bands 

 interlaminated with chlorite or as rudely formed spherules in the 



