38 
The Ohio Naturalist. 
[Vol. XIII, No. 2, 
2. Basal Bed; Red Clay Shales; Lowville. 
The oldest Ordovician rocks, in that part of Lake Huron which 
lies north of the eastern end of Manitoulin island, are exposed for a 
distance of several miles along the western shore of Cloche penin¬ 
sula, facing Cloche channel. At the northern end of the line of 
exposure these oldest Ordovician rocks rest upon and against an 
east and west ridge of quartzite mapped by the Canadian Geolog¬ 
ical Survey as Huronian. They consist of reddish clay shales 
whose thickness is not known even approximately. At one local¬ 
ity, along a small gully, a vertical section, 60 feet thick, is exposed 
above lake level, whitish limestones making their appearance 70 
feet above the lake, but the entire thickness of the red clay sec¬ 
tion probably is much greater. Fossils were found at only one 
horizon, at a locality about a mile south of the northwestern angle 
of the peninsula, where a few feet of more or less indurated, 
brownish, sandy layers are imbedded in the reddish clay section, 
a short distance above the level of the new line of railway now in 
the process of construction. Here a species of Pterotheca, closely 
allied to Pt. attenuata but only about 20 mm. in width, and a 
species of Cyrtodonta, 25 mm. long and closely related to C. jaues- 
villensis, suggest the Platteville or Lowville age of the strata 
involved. Well preserved specimens of Archinacella and Lingula 
also occur. 
3. Swift Current Beds; Chiefly Whitish and 
Reddish Limestones; Leray. 
Along the southern half of Cloche peninsula, whitish limestones 
overlie the red clays. Owing to the southward dip of the strata, 
the base of this limestone series descends to water level more than 
a mile before reaching Swift Current, the locality at which the 
railroad passes from the peninsula over to Cloche island. The 
general color of these limestones is whitish, but where they rest 
upon the Huronian quartzites, and in the immediate vicinity of the 
quartzite hills, they frequently are reddish. This reddish color 
evidently is due to the material derived from the quartzites and 
other Huronian strata which had been greatly disintegrated by 
weathering before the deposition of both the basal red clays and 
of the Swift Current limestones began. A quarry recently 
opened at Swift Current, for the purpose of providing the ballast 
needed for the new line of railway, exposes beautifully the top of a 
quartzite knoll covered by some of the upper layers of this lime¬ 
stone section. Where these limestones are in contact with the 
quartzite they not only are reddish in color but they also include 
pebbles and smaller fragmental material, evidently derived 
directly from the quartzite knoll. Among this fragmental 
material occur most of the fossils so far collected, including a 
pygidium of Bathyurus, the sipho of Actinoceras bigsbyi, a Rhyn- 
