This massive angular boulder, which is broken into two main pieces, measures about 41 by 18 metres (135 by 60 feet) and is 9 m (30 ft) high.

[1][2] Big Rock is a glacial erratic that is part of a 930 km (580 mi) long, narrow (1.00 to 22.05 km (0.62 to 13.7 mi) wide), linear scatter of thousands of distinctive quartzite and pebbly quartzite glacial erratics between 30 cm (1 ft) and 41 m (135 ft) in length.

The Foothills Erratics Train extends along the eastern flanks of the Rocky Mountains of Alberta and northern Montana to the International Border.

The boulders and smaller gravel, which comprises the Foothills Erratics Train, consist of Lower Cambrian shallow marine quartzite and conglomeratic quartzite, which occurs only within the Gog Group and is found in the Athabasca River Valley of central western Alberta.

[1][2][3][4] Near the end of the Pleistocene Period, between 12,000 and 17,000 years ago, a massive landslide occurred within the upper reaches of the Athabasca River valley.

[4][5][6] The people of the Blackfoot First Nation used Big Rock as a landmark for finding a crossing over the Sheep River (where Okotoks stands today) long before European settlement.

In the 1970s the government declared it a Provincial Historic Site to protect its geological and cultural importance.

Suddenly, the weather changed and Napi became cold as the wind whistled and the rain fell.

The deer, the bison and the pronghorn were Napi's friends, and they tried to stop the rock by running in front of it.

Pollen studies indicate that the Lower Cretaceous sedimentary strata that comprise this glacial erratic were transported a minimum distance of about 260 km (160 mi).