84 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. TO 



Britain, seem more appropriate here than in preceding parts of the 

 f)aper. 



The Stinchar limestone of the type locality rests on the Kirkland 

 conglomerate which presumably represents the clastic initial deposit 

 of the Stinchar stage of submergence. The conglomerate rests — 

 doubtless unconformably — on Radiolarian cherts and black shales 

 said to contain Arenig (UiDper Canadian) graptolites. 



Lithologically and to notable extent also faunally the upper part 

 of the typical Stinchar is strikingly like the upper part of the 

 Lenoir limestone in Tennessee and Virginia, a fact observed and 

 commented on by Professor Jones when we studied the natural 

 outcrop of the formation and its unweathered appearance in the 

 quarry. The lower part of the Stinchar also resembles lower beds 

 of the Lenoir, so that as a whole the formation strongly suggests 

 approximate equivalence to the mentioned American formation. 



The limestone exposed in the quarry at Craighead, about 3 

 miles east of Girvan and which supplied many of the distinctive fos- 

 sils of the district, is generally classed as Stinchar limestone. But 

 this correlation is almost certainly in error. The supposed age 

 equivalence of the Craighead and Stinchar limestones evidently arose 

 from the fact that Lapworth in describing the section at Craighead 

 regarded the limestone in the quarry as being succeeded normally 

 by a shale formation from which he had collected Glenkiln grap- 

 tolites. In other words, Lapworth decided that the sequence at 

 Craighead is the same as on the Stinchar where shale of Glenkiln 

 age lies in normal sequence on the typical Stinchar limestone. 



I doubt that any of our 1929 party left the Craighead quarry uncon- 

 vinced that the well displayed superposition of the shale on the 

 limestone in the quarry is due to overthrust faulting and not original 

 deposition — namely, that the Glenkiln shale has been thrust over a 

 much younger, probably Medinan, limestone formation. All agi"eed, 

 too, that the Craighead limestone is very different in lithic and f aunal 

 characters from the previously investigated typical Stinchar. So far 

 as I have been able to learn not a single species of fossils is common 

 to the limestones of the Craighead and the Stinchar. Besides, the 

 published fauna of the typical Stinchar makes but a short list, 

 whereas a total of at least 85 species has been collected from the 

 Craighead quarry limestone. 



The relations of the Craighead limestone fauna to that of the 

 Balclatchie group is much closer. In fact, of the 85 Craighead fossils 

 Reed's lists of Girvan fossils described in his monographs indicate 

 that 37 of the trilobites and brachiopods are present also in tho. Bal- 

 clatchie beds. It should be noted, however, that with very few excep- 

 tions Reed expresses some doubt regarding the actual specific identity 



