76 



bulletin: museum of comparative zoology. 



The Moneague Formation. — The Montpelier beds grade up into more 

 massive limestones, white in color, firmer in texture, often semi-crystal- 

 line, sometimes containing casts of fossil mollusks and solitary corals, 

 and occurring in well defined bands of stratification from one to five 

 feet in thickness. More massive texture and regular bedding especially 

 distinguishes this formation from the other white limestones of the 

 island, such as the chalky rocks of the underlying Montpelier and the 

 irregular lumpy texture of the overlying Cobre formations. These rocks 

 contain many cavernous moulds of Mollusca and single corals, indicating 

 that a considerable amount of shell debris may have accompanied their 

 original deposition. The fossils obtained near Ewarton, Retreat, and 

 Cinnamon Hill, in a firm limestone matrix, were mostly poorly pre- 

 served moulds of corals and mollusA:s, which the paleontologists could 

 not determine. 



These rocks become very cavernous through interstitial solution and 

 the surface is usually indurated and karrenfeldate. Sometimes the 

 limestone is in small angular fragments or lumps with sharp edges, as 

 if it had been shattered by some great stress, — a condition which may 

 in part be due to shearing, but is also largely produced by irregular 

 consolidation and solution. This angular aspect is well shown on the 

 ritrht hand side of Plate XXVI. 



Figure 24. — Residual Clays in Limestone Sinks at Frankenfield. 



In places the Moneague formation weathers into a yellow ferruginous 

 clay subsoil, constituting a thick surface coating. This is the residual 

 clay and iron which remains after the transportation of the soluble lime 

 by water. Exposures along the railway between Porus and Ipswich 

 show some beautiful subaerial alteration. Deep natural wells or pits 

 are seen in the limestone. These are filled with the residual cla}-, 

 similar to the occurrence previously shown in my report on Cuba. 

 Where the soils of these limestones have been cultivated the ruinate is 



i Notes on the Gcolopy of Cuba. — Bull. Mus. Comp. Zool. at Harvard College, 

 Vol. XVI. No. 15. 1876, Plate I. Fig. 7. 



