Qualla: Temagami Greenstone Belt

Temagami Greenstone Belt: Introduction

Mon, 23 Feb 2026 00:00:00 GMT

Photo credit P199, Public domain. Two point seven billion years. That is how long the rocks beneath the Temagami Greenstone Belt have been sitting here, in what is now northeastern Ontario, waiting for someone to notice. When the volcanic eruptions that created this narrow strip of metamorphosed basalt and rhyolite were taking place, there were no continents as we know them -- just the ancient Superior craton, a slab of early lithosphere that would eventually become the core of North America. The belt formed underwater, through eruptions that ranged from passive lava flows to violent explosions, building layers of pillow lava, pyroclastic debris, and mineral-rich intrusions that geologists are still cataloging today. It is a window into the deep past -- not deep in the human sense, but in the planetary sense, when the Earth's crust was still figuring out what it wanted to be.

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Image: P199 | Public domain

Temagami Greenstone Belt: The Fabric of the Shield

Mon, 23 Feb 2026 00:00:00 GMT

Photo credit Black Tusk, CC BY 3.0. The Temagami Greenstone Belt is part of the Canadian Shield, one of the largest single exposures of Precambrian rock on Earth. Within the belt, a remarkable variety of geologic features are packed into a relatively compact area: batholiths, volcanic complexes, layered intrusions,...

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Image: Black Tusk | CC BY 3.0

Temagami Greenstone Belt: Four Supercontinents and Counting

Mon, 23 Feb 2026 00:00:00 GMT

Photo credit Black Tusk, Public domain. The rocks of the Temagami Greenstone Belt have been passengers on a slow-motion planetary journey spanning billions of years. When the belt formed 2.7 billion years ago, it was part of the supercontinent Kenorland, a landmass that included the Baltic and Siberian shields of Euras...

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Image: Black Tusk | Public domain

Temagami Greenstone Belt: Ghosts of Prehistoric Volcanoes

Mon, 23 Feb 2026 00:00:00 GMT

Photo credit Black Tusk, CC BY 3.0. Several locations within the belt preserve evidence of ancient volcanic vents -- the throats of volcanoes that erupted billions of years ago. Remnants of a large vent lie west of Sherman Mine, where two felsic lava flows outcrop between Link Lake and Turtle Lake. The direction th...

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Image: Black Tusk | CC BY 3.0

Temagami Greenstone Belt: The Mines That Followed

Mon, 23 Feb 2026 00:00:00 GMT

Photo credit Black Tusk, Public domain. Where there are greenstone belts, there are usually mines, and Temagami is no exception. Sherman Mine, northwest of the town of Temagami, was a major iron ore producer. Mining began in 1968 across seven open pits -- North, East, South, West, and three smaller Turtle Pits. A railr...

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Image: Black Tusk | Public domain

Temagami Greenstone Belt: Deep Water, Old Name

Mon, 23 Feb 2026 00:00:00 GMT

Photo credit Black Tusk, Public domain. The name Temagami itself is Ojibwe, meaning "deep water by the shore." Until 1968 it was spelled Timagami on all official maps and documents, a spelling adopted on June 25, 1906. The change to Temagami came at the instigation of the general public, processed through the Canada Po...

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Image: Black Tusk | Public domain