128 



HARDWICKE'S SCIENCE-GOSSIP. 



in other limestone districts. I have a sketch which 

 gives a section representing the uppermost 70 

 feet of the Halkyn Mountains, locally known as 

 the Abado beds. This section consists of hard bands 

 of limestone from one to two feet in thickness with 

 several layers of shales. The sketch shows the cliff 

 as it stood in August last, but quarrying operations 

 alter its face almost daily. It is chiefly from this 

 quarry that Mr. G. \Y. Shrubsole, F.G.S., has ob- 

 tained his splendid collection of the Fenestellidse and 

 other forms of Polyzoa, from which he gathered 

 materials for his instructive paper on the reclassifica- 

 tion of the genus Fenestella, published in a recent 

 number of the Quarterly Journal of the Geological 

 Society. I believe this is the first section which has 

 been drawn of the Halkyn Mountain quarries, and it 

 may be of value to indicate the exact bands in which 



natural to suppose that the destruction was caused by 

 some sudden paroxysm of nature by means of which 

 life was extinguished and form partially obliterated. 

 The cliff there from the base to the uppermost ridge 

 is 70 feet, consisting of hard and clearly-marked 

 bands of hard limestone with occasional bands of 

 laminated shales. At the bottom of the cliff, some 

 few yards to the right of the ladder, will be found 

 the first band containing Polyzoa, at a height of 

 5 feet from the ground. At this point the shale is 

 I foot in thickness, it abounds in well-preserved speci- 

 mens of Fenestellidae. This is the only spot in which 

 this band can be examined in situ, owing to a sudden 

 dip in the strata ; the band runs up at a great angle, 

 decreasing in thickness, till it crops out at the edge 

 of the cliff some 40 feet from the ground. Thirteen 

 feet above the layer of shale comes a solid 2 feet of 



Fig. 86. — Fenestella 

 plebeia. 



Fig. 87. — Fenestella 

 plebeia. 



Fig. 90. — Fenestella plebeia. 



Fig. 88. — Fenestela 

 plebeia. 



Fig. 89. — Clauconoiiie 

 tipinnata. 



the Fenestellidae are met with. Five days have been 

 given to obtaining accurate measurements, extracting 

 the fossils in situ and tracing the various bands along 

 the whole section. It is true the face of the cliff is 

 subject to great alterations through blasting processes, 

 but, judging from knowledge of the locality, it is 

 probable that the bands of shale as now exposed in 

 the Abado quarry will remain in much the same 

 position as long as they continue to work the lime- 

 stone in a direction similar to that now pursued. It 

 is the Fenestellidae for which the locality is so noted, 

 but they are confined to three narrow bands ; end- 

 less fossils are found of various kinds in Abado and 

 neighbouring quarries, some well preserved, others 

 much crushed and partially destroyed. I have heard 

 the singular explanation of this given that it is due 

 to the huge saurians or fishes which then lived, 

 destroying as they lived. It would appear more 



limestone crammed full of badly preserved Polyzoa, 

 extremely difficult to extract on account of the hard- 

 ness of the rock, also from the fact of the cleavage 

 not being in exactly the same direction as the strati- 

 fication. Twelve feet higher will be found another 6 

 feet of well-marked bands divided by shales, in some 

 of which it is probable there is a third zone of Fenes- 

 tellidae. Although it is impossible to examine this 

 band it is certainly fossiliferous, this being proved by 

 loose bits of shale which had fallen from the particular 

 part of the rock, but we fail absolutely to identify the 

 exact layer. From these two or three bands some of the 

 most beautiful collections of Polyzoa have been recently 

 formed, and are in better preservation than from any 

 similar district in England. The dip of the upper 

 20 feet of the cliff is considerably less than that of 

 the lower portions. The lowest band of shales will 

 certainly yield the best fossils, but great patience is 



