NIAGARA FALLS AND VICINITY II 7 



is no conclusive evidence that the rock is brecciated, nevertheless 

 the coloration strongly suggests it. 



This rock is commonly very porous in its upper portion, the 

 cavities being often lined with crystals of calcite or other minerals. 

 The smaller of the cavities are due to the dissolving out of the small 

 coral, C y a t h o p h y 1 1 u m h y d r a u 1 i c u m , which was ex- 

 ceedingly abundant in the upper part of the stratum. This coral is 

 generally found in a prostrate position, with the mold perfectly pre- 

 served in the inclosing rock matrix, so that a perfect cast of the 

 coral can be obtained by the use of gutta percha or dentist's wax. 

 The best exposure of this rock is in the walls of the quarries of the 

 Buffalo cement co. It may also be seen in the face of the Onon- 

 daga escarpment at Williamsville and eastward. In many places in 

 the cement quarries, the upper part of this limestone is rich in iron 

 pyrites, which commonly occurs in small cubes, not infrequently 

 oxidized to limonite. Green stains of hydrous carbonate of copper, 

 or malachite, are not uncommon, these resulting probably from the 

 decomposition of chalcopyrite, which is disseminated in minute 

 grains through portions of the rock. Many of the geode cavities 

 contain scalenohedra or acute rhombohedra of calcite, as well as sul- 

 fate of strontian. 



A remarkable feature of the Manlius limestone of the Niagara re- 

 gion is the nature of the fossil fauna which it contains. This fauna 

 shows an intimate relation to the Coralline limestone fauna of Scho- 

 harie county (N. Y.) a rock which is regarded the eastern equiva- 

 lent of the Lockport (Niagara) Hmestone of this region. Several 

 of the species found in the Manlius limestone of this region are 

 identical with those of the Coralline limestone, while between other 

 representative species of the two formations there exists a very close 

 relationship. It is difficult to escape the conclusion that the Man- 

 lius limestone fauna of the Niagara region is a late return of the 

 Coralline limestone fauna, at the close of the long interval during 

 which the Salina shales were deposited in the Siluric seas of this 



region. 



The Siluro-Devonic contact 



The Manlius limestone of the Niagara region is succeeded by the 

 Onondaga limestone of Devonic age. The latter rests unconform- 



