130 GREAT SERPENTINE BELT OF NEW SOUTH WALES, iv., 



of Tom Tiger, and those forming the White Rocks overlooking 

 Munro's Creek (see Part ii., Plate xxiii.). Confirmation of the 

 intrusive nature of the first-mentioned group of spilites, is 

 afforded by two poorly exposed contacts, and in the last case we 

 find, on tracing the horizon of the igneous from the crags down 

 across the scree-covered slopes into Munro's Creek, the great 

 mass of White Rock is represented by a number of narrow sills, 

 all intrusive into the cherts or claystones. But, though the sills 

 often show transgressive boundaries, the general course of the 

 mass is parallel to the strike of the country. 



With regard to the statement made previously, that a lava-flow 

 occurred on Moonlight Hill, swamping the coral-limestone, some 

 modification must be made. A closer examination of the field- 

 occurrence showed that the specimen described was*not part of a 

 flow, but of a mass of agglomerate, composed almost entirely of 

 spilite-fragments, and evidently formed adjacent to the point of 

 eruption. As stated, it contains large and small masses and 

 fragments of limestone, some of which contain recognisable fossils 

 of coral. On the western side of Munro's Creek, however, 

 opposite to the Razorback, there is also an association of spilite 

 and limestone, with somewhat analogous characters. The lime- 

 stone, unfortunately, is so crystalline that no organic remains 

 are preserved. It forms a lens about seventy yards long and ten 

 wide. At its northern extremity, it is most intimately mixed 

 up with lava showing skeleton-crystals and other indications of 

 rapid chilling, and this passes laterally into a solid mass of lava, 

 containing numerous fragments of limestones and calcite-filled 

 vesicles. The igneous rock must here be an intrusive body, 

 formed probably at a small depth below the sea-floor. 



The nature of the spilite-occurrences in the Woolomin Series is 

 not clear. Dolerites have been proved to occur, and a special type 

 of spilite as yet not chemically analysed. They are rather crushed, 

 and are less variable in texture than the igneous rocks in the 

 Middle Devonian. Only one instance of pillow-structure (and 

 that a dubious one) has been seen in the spilites of the Woolomin 

 Series in the Nundle district; it occurs in a tributary of Munro's 

 Creek. Generally the rocks are quite massive, and free from 



