4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



AGE AND CHARACTER OF THE FAUNULE 



The present information is insufficient to determine the precise 

 relative age of the new faunule with respect to other known Lower 

 Cambrian faunules of North America, and in particular of the Taconic 

 sequence. The scanty stratigraphic evidence that might supply such 

 information is summarized below. 



Other fossiliferous strata form outcrops east of the bed yielding 

 the Acimetopus faunule, and a greater variety of Cambrian fossils 

 was obtained from limestone blocks in the surrounding stone walls, 

 partly derived from beds not presently exposed. The next bed to the 

 east, 45 feet higher stratigraphically than the Acimetopus stratum 

 (under the unconfirmed assumptions that the intervening beds form 

 an orderly stratigraphic succession and that the strata are not in- 

 verted), yielded a Pagetides faunule, also collected at several other lo- 

 calities in the northeastern quarter of the East Chatham quadrangle. 

 Pagetides elegans and another species of the genus are by far the most 

 common identifiable fossils in this faunule ; Olenellid fragments, Bon- 

 nia and Prozacanthoides have been observed. The third fossiliferous 

 limestone bed, which under the above assumptions would be about 450 

 feet higher stratigraphically than the Acimetopus bed, yielded Pagetia 

 and Peronopsis, almost certainly indicative of the Middle Cambrian. 

 Trilobites of the typical Elliptocephala asaphoides assemblage, such as 

 Elliptocephala itself, Calodiscus lobatus, or Serrodiscus speciosiis, have 

 never been seen at the locality, either in outcrops or loose blocks; 

 they are known in the East Chatham quadrangle only from the 

 exposures of the Ashley Hill Conglomerate (Dale, 1904; Zen, 1964) 

 whose type locality lies in the northeastern quarter of the quadrangle. 



The structure of the area is exceedingly complicated, as may be 

 observed, for example, in a deep cut on the road from North Chat- 

 ham to Maiden Bridge, which exposes a considerable thickness of 

 limestone beds interstratified with black shale. The strata appear 

 closely folded, causing some intervals to be repeated in reverse order, 

 even though the dip seems to remain fairly constant. It would be 

 difficult to discern such structures from scattered outcrops as observed 

 at the Acimetopus locality, where one might readily be misled to 

 infer an orderly succession. Limestone beds in the road cut yielded 

 a Pagetides faunule, hence they may be equivalent to a portion of 

 the section on the Griswold farm. For these reasons, the succession 

 of faunules outlined above, i.e., in ascending order the Acimetopus, 

 Pagetides, and Pagetia-Peronopsis faunules, is only suggested as 

 tentative. Talmadge (private communication) from purely strati- 



