Trips Places Foods Stories Newsletters

Take your next trip with Atlas Obscura!

Our small-group adventures are inspired by our Atlas of the world's most fascinating places, the stories behind them, and the people who bring them to life.

Visit Adventures
Trips Highlight
View all trips
Top Destinations
Latest Places
Most Popular Places Random Place Lists Itineraries
Add a Place
Download the App
Top Destinations
View All Destinations »

Countries

  • Australia
  • Canada
  • China
  • France
  • Germany
  • India
  • Italy
  • Japan

Cities

  • Amsterdam
  • Barcelona
  • Beijing
  • Berlin
  • Boston
  • Budapest
  • Chicago
  • London
  • Los Angeles
  • Mexico City
  • Montreal
  • Moscow
  • New Orleans
  • New York City
  • Paris
  • Philadelphia
  • Rome
  • San Francisco
  • Seattle
  • Stockholm
  • Tokyo
  • Toronto
  • Vienna
  • Washington, D.C.
Latest Places
View All Places »
William Sealy Gosset Plaque at Guinness Storehouse
William Sealy Gosset Plaque
Local History Museum of Treuenbrietzen
The first bunker you’ll discover, they only get better.
Goose Bay (Knik Arm) Nike Site
Interior
Kingston Penitentiary
Loading...
Recent Stories
All Stories Video Podcast
Most Recent Stories
View All Stories »
The Whitefish Point Lighthouse on the Upper Peninsula of Michigan is close to the place where the Edmund Fitzgerald went down.
Why Is TikTok Obsessed With a 50-Year-Old Shipwreck?
Why Does the Salish Sea Glow in the Dark?
The towering robotic instrument at the heart of Moving Monuments features a sustainable, modular construction—designed to be reconfigured and reborn with every performance.
Capturing Toronto’s Vibrant Rhythms in Sculpture
French artillery cannons on display in Yorktown, Virginia.
Exploring Virginia’s Historic Triangle, Then and Now

No search results found for
“”

Make sure words are spelled correctly.

Try searching for a travel destination.

Places near me Random place

Popular Destinations

  • Paris
  • London
  • New York
  • Berlin
  • Rome
  • Los Angeles
Trips Places Foods Stories Newsletters
Sign In Join
Places near me Random place
All Canada Alberta Okotoks Big Rock Erratic

Big Rock Erratic

This massive and unusual rock formation near Okotoks is the world's largest known glacial erratic.

Okotoks, Alberta

Added By
Jo
Email
Been Here
Want to go
Added to list
CAPTION
  http://en.wikipedia.org/wiki/Big_Rock_(gla...
  http://i.pbase.com/v3/82/46482/2/51631751....
  http://www.flickr.com/photos/12339061@N06/...
  http://www.flickr.com/photos/12339061@N06/...
First snowfall 2022   Donna McColl / Atlas Obscura User
Okotoks Erratic, from the other side   dmdeloach / Atlas Obscura User
Been Here
Want to go
Added to list

About

An erratic is pretty much exactly what it sounds like. Large, hulking chunks of rock, jutting out of an otherwise flat and sparse landscape, catching the eye and mystifying any comprehension of its origin.

Properly called “glacial erratics,” these rock formations are actually relatively common. Formed by dislodged rocks that traveled on top of a glacier thousands of years ago, their decidedly out-of-place appearance comes from the result of that glacier-based piggyback ride, as the melting ice deposited the far-flung rocks where they didn’t belong.

In Alberta, Canada, there is a particularly large and far-reaching trail thousands of erratics known as the Foothills Erratics Train. The Big Rock erratic is its crown jewel.

Comprised of 16,500 tons of quartzite, the Big Rock, or Okotoks, erratic is the largest known glacial erratic on the planet. Located just over four miles from Okotoks, Alberta, from which it derives its name, the massive rock formation is an unmistakable monolith in an otherwise monotonous landscape.

Despite the interesting but simple origins of this slow-forming landmark, it has long attracted legends and myths. These date back thousands of years to the Blackfoot tribe, whose legends explained the rock’s peculiar location by detailing an argument between the rock and a young warrior that eventually gave way to a frantic chase and the eventual splitting of the rock down its center.

Today, mysticism-minded travelers still find themselves drawn to the Big Rock, usually avoiding the scientific explanation for the unusual formation, instead preferring to make up their own stories as time goes on. 

Related Tags

Natural Wonders Geological Oddities Geology Nature

Know Before You Go

The Okotoks Erratic is located off Highway #7, with its own parking lot nearby. It is about 10 kilometres southwest of Okotoks, 15 kilometers northeast of Black Diamond, or an hour's drive from central Calgary.

Community Contributors

Added By

canuck

Edited By

pjrussell, Pengwn, King Slender, olgafowler450...

  • pjrussell
  • Pengwn
  • King Slender
  • olgafowler450
  • Mark Casey
  • Donna McColl
  • dmdeloach

Published

July 24, 2012

Edit this listing

Make an Edit
Add Photos
Big Rock Erratic
AB-7, Foothills No. 31
Okotoks, Alberta, T0L 0H0
Canada
50.705929, -114.076247
Visit Website
Get Directions

Nearby Places

Little Chief

Calgary, Alberta

miles away

Reader Rock Garden

Calgary, Alberta

miles away

Rundle Ruins

Calgary, Alberta

miles away

Explore the Destination Guide

Photo of Alberta

Alberta

Canada

Places 81
Stories 5

Nearby Places

Little Chief

Calgary, Alberta

miles away

Reader Rock Garden

Calgary, Alberta

miles away

Rundle Ruins

Calgary, Alberta

miles away

Explore the Destination Guide

Photo of Alberta

Alberta

Canada

Places 81
Stories 5

Related Stories and Lists

13 Places to Celebrate Erratic Behavior

List

By Gemma Tarlach

Related Places

  • Winona, Missouri

    Rocky Falls

    A 40-foot waterfall flows into this unique natural swimming hole.

  • Slumgullion mass wasting area

    Lake City, Colorado

    Slumgullion Earthflow

    This National Natural Landmark is one of the best examples of a “mass wasting” in the world.

  • Looking Glass Rock seen from the Looking Glass Rock Overlook on the Blue Ridge Parkway

    Brevard, North Carolina

    Looking Glass Rock

    This granite rock face is named for the magnificent reflection that occurs when the sun hits it just right.

  • Sasso Menicante on Monte Cimino

    Soriano nel Cimino, Italy

    Sasso Menicante (Trembling Stone)

    This massive rock balanced for thousands of years being tossed here during a volcanic eruption.

  • Macquarie Island lengthwise, the research station at center.

    Australia

    Macquarie Island

    One of the only places where Earth’s mantle lies above water.

  • Bonhomme de Bourail

    Bourail, New Caledonia

    Bonhomme de Bourail

    A beachside monolith shaped by years of waves crashing against hard quartz.

  • The metal pillars aligned to form the Old Man’s face

    Franconia, New Hampshire

    Old Man of the Mountain Profiler Plaza

    A serene plaza that commemorates one of the Granite State's most iconic figures.

  • The salt lake becomes colorful in warm temperatures because of algae growth

    Yuncheng, China

    Yuncheng Salt Lake

    Rainbow-hued in the summer and crystalline in the winter, this salty lake has inspired battles, temples, and plenty of awe.

Aerial image of Vietnam, displaying the picturesque rice terraces, characterized by their layered, verdant fields.
Atlas Obscura Membership

Become an Atlas Obscura Member


Join our community of curious explorers.

Become a Member

Get Our Email Newsletter

Follow Us

Facebook YouTube TikTok Instagram Pinterest RSS Feed

Get the app

Download the App
Download on the Apple App Store Get it on Google Play
  • All Places
  • Latest Places
  • Most Popular
  • Places to Eat
  • Random
  • Nearby
  • Add a Place
  • Stories
  • Food & Drink
  • Itineraries
  • Lists
  • Video
  • Podcast
  • Newsletters
  • All Trips
  • History & Culture
  • Wildlife & Nature
  • FAQ
  • Membership
  • Feedback & Ideas
  • Community Guidelines
  • Product Blog
  • Unique Gifts
  • Work With Us
  • About
  • FAQ
  • Advertise With Us
  • Advertising Guidelines
  • Privacy Policy
  • Cookie Policy
  • Terms of Use
Atlas Obscura

© 2025 Atlas Obscura. All Rights Reserved.