BY G. D. OSBORNE. 163 



II. Kuttung Series. 



(i.) Wallarobba Beds. — Basal conglomerates and tuffs with the con- 

 glomeratic material predominating. Thickness, 2500-3000 feet. 



(ii.) Martin's Creek Beds. — Lavas and tuffs with intercalated con- 

 glomerates. Thickness, about 2250 feet at two localities, viz. Martin's Creek 

 and Eelah. 



(iii.) Mt. Johnstone Beds. — A series of tuffs, cherts and conglo- 

 merates containing remains of the Rhacopteris flora and impure coal seams, these 

 beds being capped by an acid lava flow of toscanite (Paterson type). Thickness: 

 Tuffs, conglomerates, etc., 1950 feet; Toscanite, 300 feet. 



(iv.) Glacial Beds of Seaham and Paterson. — Fluvioglacial conglomerates, 

 tillites, varves and tuffs. Thickness, 1840 feet. 



DETAILED STRATIGRAPHY OF THE CLARENCETOWN-PATERSON 

 DISTRICT. 



Preliminary. 



In connection with the present work, more detailed observations were made 

 upon the Kuttung than upon the Burindi Series, the main igneous portion of 

 the Kuttung Series being the subject of the most careful attention. Definite 

 "indicator" horizons were surveyed in detail, in order that the geological struc- 

 ture might be made apparent, and this method afforded excellent opportunities 

 for observing the distribution of the various horizons in the Series. It was soon 

 evident that the succession at any one locality was not in detail the same as at 

 any other, and for this reason detailed sections have been prepared to show 

 the variation in the degree of development and order of the various units. After 

 consideration of the statement that the sequence is different in different localities, 

 one might arg-ue against the policy of mapping any particular horizon to de- 

 lineate the geological structure. However, the only units used in this connection 

 were the hornblende-andesite (Martin's Creek type) and the biotite-toscanite 

 (F'aterson type), which were sufficient to provide the evidence for interpreting 

 the broad tectonic features of the area. In addition, other junctions, and three 

 well-defined horizons in the main igneous portion of the Series have been mapped 

 to show the distribution of the latter and to supply collateral information as 

 to structure, 



The two fii'st-mentioned horizons form limits to the portion of the Kuttung 

 Series in which stratigraphical variation occurs, and experience has shown that 

 each of these two units occupies a constant stratigraphical horizon. 



The question as to whether some of the massive igneous rocks are flows or 

 intrusive bodies may be considered here. (There are some definitely intnisive 

 rocks in the area, possibly of age later than Cai'boniferous, which will be 

 described later). The massive igneous rocks in the Kuttung Series comprise 

 rhyolites, toscanites, dellenites, keratophyres, dacites, andesites and andesitic 

 pitchstones. There is no doubt as to the nature of the acid and sub-acid types 

 except the Paterson type of toscanite and dellenite, which are considered below 

 (p. 181). But the following evidence supports the contention that the acid 

 types in the main igneous portion of the Kuttung Series (hereafter called the 

 Volcanic Stage) are extrusive: There occur in the area tuffs of similar general 

 composition to these massive rocks, and in the coarser fragmental material, some 

 of the inclusions are identical with certain of the massive rocks. In many cases 

 spherulitic and axiolitic structures abound in the base of the porphyritic types 

 and, in some instances, the rocks may still come under the categoi-y of "massive 



