His interest in the mineral world started during his undergraduate studies at the University of Toronto, where he excelled at chemistry, biology, mineralogy, and geology. After graduating, he thought he would go into law but a threat of tuberculosis made him change his mind. He opted for the outdoor life of a geologist.

Working at the Geological Survey of Canada from 1880 on, Tyrrell made traverses through the Crows Nest, Kootenay, and Kicking Horse passes in the Rocky Mountains, as well as in Alberta.

By the end of the 19th century, he decided to explore the Pre-Cambrian shield area of northern and Arctic Canada, where he made a series of journeys by wagon and canoe. One of such treks took him from the Lake Athabasca Post of the Hudson’s Bay Company to the Barren Lands, the treeless arctic wastes lying to the west of Hudson Bay.

Once he finished his northern expeditions, where he also documented glacial geology and confirmed that three Pleistocene ice sheets had covered northern and eastern Canada, he was moved to the Yukon. It was the time of the Klondike gold rush which interested him so much that, upon his return to Ottawa, he quit his job and went into the private sector to be able to go back to the territory. To do so, he became a geological and mining consultant and quickly won the confidence of gold miners operating in the area.

According to the Complete Dictionary of Scientific Biography, Tyrrell’s career in the Yukon saw him contributing to the geology of alluvial gold and learning about the transition from streaming to large-scale hydraulic mining.

In 1894, he married Mary Edith Carey, who would later become the founder and first president of the Women’s Association of the Mining Industry of Canada.

In 1895, the couple returned to the east. Tyrrell became a consultant in Toronto and was retained by the Anglo-French Mining Company of London. During this period, he focused his attention on the silver mining district of Cobalt, located in eastern Ontario. At the same time, he discovered the Kirkland Lake gold deposit, which he predicted from structural reasoning. “The sinking of a 600-metre shaft proved the orebody and led to the founding of the highly successful Kirkland Lake Gold Mining Company. Tyrrell was president of the company until a few years before he died,” the Complete Dictionary of Scientific Biography states.

After a career in mining that lasted for more than five decades, Tyrrell retired to northeast Scarborough on the Rouge River, where he established apple orchards. He died in Toronto in 1957 at the age of 98.