170 F. L. Stniivell: 



most extensively along a side gully and the bed of the tributary 

 creek, from which it has been omitted from the quarter sheet. In 

 places along the main stream — e.g., the point marked D on the 

 map from which a specimen was collected and analysed, it may 

 be observed to rest directly and unconformably on the folded 

 Silurians. It is not bedded, nor continuous, and is very vari- 

 able in character. At the point marked C on the map, close 

 to the boundary of the allotments X. and XIV., is a small excava- 

 tion in the limestone rock from which a sample was taken and 

 also analysed. Here it is a very hard, grey rock which weathers 

 on the surface to a dull white, and which contains small dissem-^ 

 inated quartz grains and scattered lumps and boulders of a 

 scoriaceous and weathered basalt, such as is found on the surface 

 of flows. At the locality D on the boundary of allotments IX. 

 and XIV., it is of a white colour, much softer, and contains a 

 great deal more quartz and other impurities. In addition to 

 these two types there are many variations. It is found in every 

 condition between the above and a black marl, when the per- 

 centage of admixed river silt is very large. In one section of 

 creek alluvium it is found in the form of nodules in horizontal 

 layers. This alluvial material is derived in part from the 

 Silurian rocks, in part from the basalt, and in part from the 

 limestone, and therefore contains much magnesia. Rain water, 

 on passing through, has partly dissolved out the lime and 

 magnesia, and by means of the concretionary process has re- 

 deposited the carbonates in more or less horizontal rows of 

 lenticular concretions. 



Fresh-water shells are to be found enclosed in the limestone in 

 the bed of the creek, and more abundantly in the tributary 

 creek. A specimen w^as very kindly examined by Dr. Pritchard, 

 who stated it to be Pomatnpyrgus huccinoides, Quoy and Gai- 

 mard, a species which may still be obtained living in the creeks 

 in great numbers. Dr. Pritchard also tells me that some of 

 limestone patches are made up very largely of Coxiella confusay 

 E. A. Smith. The late Professor McCoy originally referred to 

 material from this locality as containing Truncatellas, but Dr. 

 Pritchard has not seen any of this genus, and is inclined to think 

 that perhaps Co^J-ieZZa was the shell referred to by Professor McCoy. 



