This is the 7th book in a series of roadside geology books. In this book, we focus on the Precambrian bedrock geology along Ontario routes 546, 639, and 108. There are 22 individual outcrops along with background geologic information. The locations in this book have not been included in my other roadside books. The book is paperback and in full color. It follows the typical layout of my other roadside books. The Precambrian rocks explored are as old as Archean but most are of the younger Paleoproterozoic Huronian Supergroup. These rocks are 2.5 billion to 2.2 billion years old and were deposited during a great time of change on Earth. This is the first time we see modern Plate Tectonics in action. Oxygen was being pumped into the atmosphere for the first time. It is also a time of glaciation, perhaps the oldest.