No. 8.] SPENCER — GEOLOGICAL SKETCHES. 465 



were associated with numerous specimens of Modiolopsis. They 

 appeared for a time to be confined to the one locality mentioned, 

 but recently I have found them near the city. Though bright 

 blue when first taken out, they soon become quite dull. 



Several fine varieties o^ Butliotrepliis gracilis, and one or two 

 other plant remains are found in the Clinton. 



As almost all the animal remains of this formation are found 

 in the Niagara, only a few species, that are less common above, 

 or locally not met with there, will be enumerated, viz. — Steno- 

 pora fibrosa, Ileliopora fragiiis, Trematoporafahulata, Clathr'o- ' 

 pora frondosa, Ptilodictya crassa, Ortliis Ii/nx, 0. Davidsonl, 

 0. elegantula, Athyris naviforinis, RhynchoneUa, neglecta, R. 

 rugosa, Avicula emacerata, numerous Modiolopses, Cyrtodonta, 

 Tentaculites distans, etc. The Li^igulw above mentioned belong 

 principally to L.oblonga, L. ohlata and L. cuneata. Col. Grant 

 has found one or two specimens of Recepticulites, and a few 

 netted graptoites in the Clinton. 



The Niagara Formation. 



This constitutes the upper portion of the escarpment, and ex- 

 tends over a considerable area, frequently cropping out through 

 the drift. Of the rocks deposited during the Niagara epoch 

 only 63 feet in thickness remain at Hamilton, while at Dundas 

 the formation reaches double this thickness. 



The following is a section of the Niagara Formation at Ham- 

 ilton, in ascending order : 



1. Hard gray magnesian limestone, weathering yel- Ft. Ins. 



lowish, and holding Pentamerns oblongus^ and in 

 the lower part containing Lingulx, which a few 

 feet below in the Clinton are coloured blue.... 1 6 



2. Bluish, argillaceous and arenaceous shales, with 



some bands of arenaceous, argillaceous, or mag- 

 nesian limestones 21 6 



3. Hard magnesian limestone with geodes of calcite, 



barite, selenite, gypsum, celestite, pyrite, etc. 5 



4. Thin beds of limestone, in some cases argillaceous, 



separated by layers of dark bituminous shales, 



some of which contain graptolites 9 



5. Compact magnesian limestone, known locally as 



the " Blue Building Beds." Some of the heda 

 weather into pits on the surface, and are separa- 

 ted by shaly partings. Fossils in considerable 

 quantities are found in these beds, especially 

 Trilobites 14 U 



6. Gray magnesian limestone, exceedingly cherty, 



and containing numerous remains of sponges, and 

 reticulated graptolites in places, besides a large 

 number of other fossils 12 



00 63 ft. 



