Tol. 55.] ON PALEOZOIC EADIOLABIAN EOCKS IN N. S. WALES. 25 



nated, the laminse of deposition being about 1 mm. thick. The 

 base in which the tests occur is very fine-grained, the particles 

 being from 0*025 to 0*05 mm. in diameter, and in places the 

 cherts and clay-shales are streaked and spotted with finely-divided 

 carbon. That the base is not wholly siliceous, as it would be if 

 entirely derived from the breaking-down of the radiolarian tests, is 

 rendered probable by the chemical analysis of radiolarian shale 

 collected by us near Tamworth Common, and apparently exactly 

 similar to that now under consideration, which shows that the shale 

 contains 15 per cent, of alumina. 



The massive coral-limestone crops out in Tamworth Temporary 

 Common. A good section of this and of the overlying cherts, 

 claystones, and radiolarian limestones may be studied in the quarry 

 on the left bank of the small creek which flows through this part 

 of the Common. A section of these and of some of the tuff -beds 

 is shown in PI. III. (N'umerous smaller intervening beds have 

 been omitted.) 



The limestone has a general westerly to west-south-westerly dip 

 at 45° to 57°, and, so far as can be judged, is about l*iO feet thick at 

 this point. It thickens, however, considerably northward, being about 

 1000 feet thick in the parish of Woqjomol, some little distance to 

 the north-north-west. The colour varies from white to bluish (dark) 

 grey. It contains corals, hydrocorallines, and in places crinoids, in 

 great abundance. Among the hydrocorallines Stromatoporella is 

 very common, while among the corals the following predominate : — 

 Pacliypora and Alveolites alveolaris, both extremely abundant; 

 Eeliolites, plentiful; as well as several species of Syringoj^ora^ 

 DijyliypJiyllum Forteri, and Cystiphyllum. 



A comparison of the section here with that described at the 

 eastern end, commencing with the garnetiferous limestone, has led 

 us to the conclusion that the two sections are identical, and that 

 consequently there must be a great fault throwing easterly towards 

 the granite-massif. It is this fault which has caused a repetition 

 of the beds, and its throw must amount to 9000 feet. The suppo- 

 sition as to the existence of the fault is confirmed by the structure 

 of the limestone-bed at the top of its outcrop, as it is sharply folded 

 over, so as to dip steeply towards the east — that is, towards the 

 fault-plane, as shown in PI. III. 



The arguments in favour of this fault are chiefly as follows : — 



(1) The fact that the limestone on the eastern side of the anti- 

 cline dips eastward and that a little farther east the strata dip 

 persistently westward, and yet the limestone does not reappear at 

 the spot where it should do so if the strata, e. g., of the anticline 

 formed a trough. On the contrary, the strata east of the anticline, 

 for a considerable distance, do not contain any thick bed of lime- 

 stone, but consist chiefly of claystones, tuff's, with occasional thin 

 bands of radiolarian limestone for about 2| miles eastward, where 

 the garnetiferous limestone (a repetition, according to our view, of 

 the coral-limestone) is rsached near the eastern extremity of the 

 line of section. 



