Red Rock
Text from the plaque
One of Ontario's most striking geological formations, this cuesta has at its base granite rocks formed deep in the Earth some 2,500,000,000 years ago and exposed after millions of years of erosion. Subsequently a thick deposit of sediment accumulated, possibly in the waters of an inland sea that once covered this region. The sediment was converted by pressure into layers of shale, impure limestone and sandstone, red in colour owing to the presence of iron-bearing hematite. A molten material, diabase, later forced its way horizontally between the sediments forming a 'sill' which was uncovered by subsequent erosion. This is the dark rock capping the hill. Its columnar structure was produced by shrinkage during the cooling process.
Transcribed from the marker, not summarised.
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The District of Thunder Bay
The Township of Red Rock
On Highway 11/17, west of Nipigon between Highways 585 and 628
(unknown)