<50 Harris and Crawford: 



(ii.) Diplograptus-Climacograptus shales are interstrati- 

 fied with the Grits (though naturally graptolites are 

 hard to find), and remains of Diplograptus occur in 

 the Grit itself at some localities. At one outcrop — 

 on the Western Kororoit Creek — sandstones appar- 

 ently of the Grit series, yielded from thin, included, 

 impersistent shales Dicellograptus, as well as Diplo- 

 graptus. The sandstones in this case were not quite 

 typical Riddell Grit, but we believe them to bejong to 

 that series. 



(iii.) The fauna of the Grits, other than graptolites, in 

 Mr. Chapman's opinion is Silurian, and even Yerin- 

 gian (Upper Silurian). Mr. Chapman states: " The 

 fossils indicate a mid or newer Silurian horizon. As 

 a distinct horizon of grits, I should say they were 

 basal, and, from the fossils, basal Yeringian. The 

 Leptaena is of a type only found in the Newer 

 Silurian, as also the Encrinurus and cf. Eridotrypa. 

 The faunal elements suggesting an older phase of the 

 Silurian, are the abundance of Camarotoechia and 

 Rhynchotrema" 



(iv.) Though there is no evidence of the fact, the Grits 

 may not be all of the same series. Mr. Chapman states 

 that as far as the fossils go, there is no evidence of 

 more than one horizon, and there is a remarkable 

 similarity in the appearance of the Grits at. all out- 

 crops. Still, at Springfield, east of Romsey, a litholo- 

 gically similar band is interstratified with Mono- 

 graptus shales. 



Having stated some of the difficulties of the question we shall 

 mow proceed to discuss it. 



(b) Field Relations — Critical Localities. 



(1) Mouth of Watson's Creek — " Dalrymple's." 

 Following Watson's Creek to the north-east from the Mount 

 Alexander Road, a walk of less than two miles brings one to its 

 junction with Jackson's Creek, which here swings in from the west 

 through a narrow gorge in the basalt, meanders through a small al- 

 luvial flat, and then continues eastward, hugging, the foot of a high 

 northern bank. This is an interesting locality, though, like many 

 critical sections, its interpretation is difficult. (See Fig. 2.) 



