The Bull Lake glaciation is the name of a glacial period

Glacial period

A glacial period is an interval of time within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate within an ice age...

 in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 that is part of the Quaternary Ice Age

Quaternary glaciation

Quaternary glaciation, also known as the Pleistocene glaciation, the current ice age or simply the ice age, refers to the period of the last few million years in which permanent ice sheets were established in Antarctica and perhaps Greenland, and fluctuating ice sheets have occurred elsewhere...

. The Bull Lake glaciation began about 200,000 years ago and ended about 130,000 years ago, and was concurrent with the Illinoian Stage of the Quaternary Ice Age. There is disagreement over these time frames, however, and further research is necessary.

This glacial period was identified by geologist

Geologist

A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...

 Eliot Blackwelder.