278 OBSERVATIONS ON THE GEOLOGY OF THE WESTERN PENINSULA 



and the Oriskany sandstone is altogether absent at the Niagara River. The 

 Rocks which have thus disappeared in going westward through New York, 

 comprise, with the exception of the Hydraulic limestone, all the members of 

 formations six and seven of the Appalachian System of Pennsylvania and 

 Virginia. 



In approaching the interior of the Peninsula of Upper Canada, we have 

 evidences of a further change in the formations; the Corniferous and Onondaga 

 limestones appearing to cease altogether before we mark the eastern shores of 

 Lake Huron, and the Hydraulic and Seneca limestones either, likewise, disap- 

 pearing, or so changing their type, as to make their recognition uncertain. 



A group of limestones resting on the pitted rock about thirty miles above 

 London, on the north branch of the Thames, seems to embrace a stratum re- 

 ferable to the Onondaga rock ; but on the Maitland River near Goderich, where 

 the series is well exposed, none of the formations developed east of Buffalo, 

 excepting the well characterized pitted limestone, could be identified. 



The following section of the strata exposed in the cliffs of the Maitland, 

 conveys, we believe, a correct idea of the general order of superposition of the 

 limestones of the south-western part of the peninsula of Upper Canada. 



1. Ascending the River from the bridge near Goderich, the lowest stratum 

 seen near the water's edge is a fawn-coloured slaty limestone of fine texture, 

 containing hopper-shaped cavities, and a few fossils. This rock was recog- 

 nised as belonging to the upper part of the gypseous shales. 



2. A buff-coloured arenaceous limestone, striped with various shades. It is 

 often merely a calcareous sandstone, of variable composition, occurring in lay- 

 ers from six inches to two feet thick. It contains a delthyris, but not in consi- 

 derable numbers. 



3. Above the last occurs an arenaceous and argillaceous rock of a yellow or 

 buff-colour, and very rough worm-eaten aspect. It is soft, and contains geodes 

 or nests of carbonate of lime and sulphate of strontian, the removal of which 

 has caused its cavernous structure. This bed is several feet thick. 



4. The next higher mass is a bed about two feet thick of the pitted rock of 

 the gypsum. This is an impure buff-coloured soft limestone which breaks at 

 right angles to the bedding. It corresponds in all respects to the rock seen at 

 Paris, Syracuse and other places, in association with the gypseous shales. 

 This is the highest layer exposed near the bridge; but, ascending the stream, 

 we find excellent exposures along both its banks. 



