INCLUSIONS OF BASIC PLUTONIC ROCKS AT KIAMA. 65 



On the OCCURRENCE of INCLUSIONS of BASIC 

 PLUTONIC ROOKS in a DYKE NEAR KIAMA. 



By C. A. Sussmilch, f.g.s. 



[Read before the Royal Society of N. S. Wales, September 6, 1905. ,] 



The inclusions (Xenoliths) referred to in this note were 

 obtained by Mr. E. A. Perry and myself from the Bombo 

 Quarries, which are situated at Bombo Point, about two 

 miles north of Kiama. They consist of rounded fragments 

 from 1 to 7 inches in diameter, embedded in a basic dyke 

 rock, which microscopic examination shows to be a monchi- 

 quite. The permo-carboniferous lava flows, in which the 

 Bombo quarries occur have recently been described by 

 Messrs. J. B. Jaquet, G. W. Card, 1 and L. F. Harper, as an 

 orthoclase basalt, and in the same paper they also map and 

 describe a number of dykes of olivine basalt and monchiquite 

 intruding these flows at Bombo Point. The specimens con- 

 taining tlie plutonic inclusions were found near the north- 

 east of the quarry, as loose fragments on the quarry floor. 

 A careful search failed to obtain them in situ. A micro- 

 scopic examination of the monchiquite shows it to be 

 identical with that described from the dyke No. 36 on the 

 map accompanying the above mentioned paper, and if this 

 dyke continues in the direction indicated, it would cross 

 the quarry just about at the place where our specimens 

 were obtained. There is little doubt therefore that these 

 specimens formed part of a continuation of this dyke. 



1 Geology of the Kiama-Jamberoo Districts. — Records of the Geological 

 Survey of N.8. Wales, Vol. vin., part i., by John B. Jaquet, a.r.s.m:., f.g.s.>. 

 George W. Card, a.r.s.m., f.g.s., and L. F. Harper, f.g.s. 



E-Sept. 6, 1905. 



