207 



admittedly unlike any others, fossil or recent, and thus canuot 

 serve for comparison. For the remainder, close analogies are 

 claimed with shells in the European tertiaries, viz., seven with 

 Eocene, one with Oligocene, five with Miocene, and one with 

 Pliocene forms. Even in this short list of fossils the balance is 

 if anything favourable to the Eocene rather than to the Miocene, 

 though with the extremely rich fauna of our tertiaries a decision 

 either way was at the time necessarily premature. 



In the second place, the beds at Spring Creek were divided 

 into upper, middle, and lower Miocene. Waiving for a moment 

 the question as to their being Miocene at all, we conclude, after 

 a careful study of the section, that there is no evidence to justify 

 a tripartite division of the strata, except that afForcled by 

 lithological differences. Sections of great thickness, and as a whole 

 rich in organic remains, do usually show a diminution in the 

 numbers of fossils, both specifically and individually, as they are 

 traced to higher levels ; but it does not necessarily follow that 

 there is a paheontological break between the upper and lower 

 portions. In the original memoir a distinction was made 

 betw^een beds containing bivalves and others underlying them 

 containing chiefly univalves. This distinction does not exist. 



The upper portions of the cliffs are, it is true, not easily 

 accessible ; but huge fallen masses detached from near the top 

 have yielded numerous fossils, wdiilst intermediate portions are 

 brought within range of observation in consequence of their dip. 

 Those at the bottom are, as might be expected, the best pre- 

 served, and even 20 or 30 feet up many of the most fragile shells 

 have perished, strong bivalves, such as Pectunmdus, Cardita, 

 Limopsis, Cuculhea, Chione, ttc, chiefly weathering out on the 

 face. From this circumstance has arisen the mistake that 

 separate geological horizons are represented at different heights. 

 The bivalves, brachiopods, and echinoderms supposed to be 

 characteristic of the upper zones are also found at the base of 

 the section, while the univalves, as Typhis^ JIurex, Voluta, 

 Cancellaria, &c., are by no means confined to the lowest strata, 

 but may be collected not only in the fallen masses referred to, 

 but also as high up the cliffs as it is possible to reach, though in 

 the latter position more or less decomposed, and in diminished 

 numbers. 



According to the Survey, the univalves are at the base of the 

 section ; then come the bivalves, and at the top the brachiopods 

 and echinoderms. Now, at the northern end of the section the 

 dip of the strata actually brings a well-marked bivalve-band down 

 below sea-level, and it passes out of sight; while above it the 

 univalves exist in greater profusion than in any other portion of 

 the whole exposure ! Again, on the southern side the polyzoal 



