Deep Bay
Key facts
- Country
- Canada
- Diameter
- 13 km
- Age
- about 99 ± 4 million years
- Location
- 56.40° N, 102.98° W
A round bay about 13 km across at the southern end of Reindeer Lake, Saskatchewan, unusually deep compared with the shallow lake around it.
Deep Bay is an impact crater about 13 km across forming a round bay at the southern end of Reindeer Lake, in north-eastern Saskatchewan, Canada. It earns its name: the bay is more than 200 m deep, many times deeper than most of the surrounding lake.
Discovery. The round shape and great depth of the bay stood out on maps and depth soundings, and in the 1960s geologists studying craters on the Canadian Shield investigated it. Sediment cores and samples from the bay floor contained breccia and quartz grains with shock features, showing that it was an impact crater.
What it hit. The impactor struck ancient crystalline rocks of the Canadian Shield, mainly gneiss and granite around 1.8 billion years old. After the impact, sediments collected in the crater, and some of this fill survives on its floor beneath the water.
Age. Dating gives an age of about 99 million years, in the Cretaceous, with an uncertainty of a few million years.
Why it matters. Deep Bay shows how a crater in hard rock can survive as a basin long after it forms, even after repeated scouring by ice sheets. The impactor is unknown.
Visiting. The area is remote but accessible by boat and floatplane. Reindeer Lake is large and its weather can change quickly.
Did you know?
Deep Bay is more than 200 m deep, far deeper than most of Reindeer Lake.
Some of the sediment that collected in the crater after the impact still lies on its floor, under the water.
It was studied in the 1960s during a search for craters on the Canadian Shield.