SILURIAN. 257 



supposed to be in a general way equivalent on opposite sides of the faults, appear in different 

 parts to be modified in volume and somewhat in Uthological character by different degrees of 

 metamorphic action. 



• The intrusive relations of the igneous rocks and the metamorphosed condition 

 of the sediments, particularly on Sop's Arm, are described by Murray, who states 

 further : 



Between the conglomerates of Sop Island and those of the eastern end of Sop's Arm the 

 rocks of the western part of Sop Island, of Goat Island, and of the main coast appear to be 

 slates of various shades of green, often marked by pink calc spar in nodules, patches, and short 

 veins; of occasional interstratified sandstones, sometimes fit for flagging, with calcareo- 

 arenaceous bands; and occasional impure limestones, weathering brownish. East of Bartlet's 

 Cove, which is an indentation on the south side of the southwestern extremity of Sop Island, 

 there was seen a thickness of 50 feet of black slates. These rocks are, in several places, charac- 

 terized by fossils, which are somewhat obscure; but though few of them could be specifically 

 determined, they have yet, according to Mr. Billings, a general aspect allied to that of Upper 

 Silurian types. It would, however, for the present, be impossible to say to what horizon in 

 the series the different divisions of the rocks of Jackson's Arm and of Sop's Arm may belong, 

 and it may be proper to remark that while no doubt is entertained of the general equivalency of 

 the rocks of the two localities, all the places in which organic remains were observed occur ia 

 the neighborhood of Sop's Arm. 



One of these localities is Bartlet's Cove. Here the fossils occur in calcareo-arenaceous 

 flagstones, and the genera observed, in addition to numerous fucoids and crinoidal stems, were a 

 Murchisonia, an Orthoceras, and a Graptolithus. At a point on the main coast halfway between 

 Spear Point and the promontory occupied by the porphyry which strikes from Sop Island 

 organic remains were met with in strata somewhat similar to those of Bartlet's Cove ; they con- 

 sisted of fucoids, crinoidal stems, and an Orthoceras. On the western side of Goat Island, 

 still in the same description of strata, in addition to fragments of crinoidal columns, there were 

 met a Syringopora and Favosites gotMandica. 



In Murray's report for 1871,"°*'' based on Howley's exploration of Exploits and 

 Gander bays and vicinity, the Silurian is described as the " Upper, unconformable 

 formation," which is said to occupy a rudely elliptical trough. 



The evidences, so far, tend to show that while the formations butt up against the Quebec 

 group on the northern and southern sides of the trough, they overlap the junction of the latter 

 at the eastern and western extremes. 



The central part of this elongated trough has been greatly disturbed for the whole length of 

 its course, froin the head of the Red Indian Pond to the Dildo Run, where vast dikes were seen 

 to cut through the strata at very many parts, while great areas are spread over by overflows of 

 trap, or breccious intercalations. * * * 



The base of the Upper and unconformable formation consists of conglomerate and sand- 

 stones, with slaty divisions, which, at Goldson's Sound, seem to come against the older and 

 altered roclis in a slightly oblique direction, as if brought into their present position by a fault, 

 the lower beds dipping about S. 55° E. <24°. The lower conglomerates are of a reddish 

 general color, the matrix being constituted of fine reddish sand, sometimes slightly calcareous, 

 which incloses well-rounded pebbles of quartz, red jasper, green jaspery slate, and fragments 

 of magnesian rocks. The pebbles are not usually large, the largest being about the size of a 

 hen's egg. The strata in ascending succession are still of conglomerate character, but the color 

 gradually passes into gray, and there are numerous pebbles of gneiss and syenite mingled with 

 the other qualities, and they are frequently characterized by the presence of hard blue or 

 blackish cherty concretions, which weather a bright yellow, are sometimes concentric in structure, 

 and of an elliptical shape. The islands of Goldson's Sound expose an alternation of conglomer- 

 ates and red sandstones, with dark-gray slates, which are themselves occasionally finely con- 

 48011°— 12 17 



