Skip to content
Geological Society of Minnesota
Road Marker
Facebook Facebook
Search
  • Welcome Page
  • Marker Home Page
  • View Road Marker from Map
  • View Road Marker by List
  • Do-it-yourself Geology Field Trips in Minnesota
  • Information on Geographical Coordinates
  • Send Road Marker Information or Question
  • Welcome Page
  • Marker Home Page
  • View Road Marker from Map
  • View Road Marker by List
  • Do-it-yourself Geology Field Trips in Minnesota
  • Information on Geographical Coordinates
  • Send Road Marker Information or Question
Geological Society of Minnesota

Road Marker Views

  • Where Found
  • Find by GPS
  • by Region
  • by County
  • Marker Status
  • by Do It Yourself Region
Title: Glacial Potholes
Road Markers

Description:

Minnesota Potholes. 

Google Map panorama image of the Pothole.

The St. Croix Dalles (Home of the World’s Deepest Potholes)

More Info.

 

Enter Road Address in your cars GPS:
307 Milltown Rd, Taylors Falls, MN 55084

OR
Enter Geographical Coordinates in your cars GPS:

Degrees Lat Long:   45.399417, -92.651556

Latitude:      45°23’57.9″N
Longitude:   92°39’05.6″W

Go to Google Map

Country: Chisago County
Where Found:

 Marker is in Taylors Falls, Minnesota, in Chisago County. Marker can be reached from U.S. 8 near Bench Street. Marker is in Interstate State Park (vehicle permit required) beyond the Visitor Center.

Marker Number:4
Marker Composition: Stone with Bronze plaques

Text on Marker:

Glacial Potholes

The potholes at the St. Croix Dalles have their origins in a tale of fire and ice. They are carved in a dark volcanic rock called basalt, which erupted as lava 1.1 billion years ago. This basalt is related to lava flows that line the North Shore of Lake Superior. About 500 million years ago, when shallow tropical seas covered this area, the basalt was buried beneath a thick blanket of sand, which later became sandstone.

During the last two million years, glaciers have advanced from the Ontario region through the Lake Superior basin, repeatedly covering the Taylors Falls area. About 12,000 years ago, near the end of the most recent glaciation, meltwater collected at the southwestern edge of a glacial lobe as the lobe receded into the Superior basin. This water formed a growing Glacial Lake Duluth. When Glacial Lake Duluth drained, great floods flowed southward through the St. Croix River valley, forming Glacial River St. Croix. The largest of these floods was perhaps a hundred times the volume of modern ones. At this time, Glacial Lake Duluth drained only via Glacial River St. Croix, because ice still blocked the Superior basin’s eastern outlet to the lower Great Lakes.

Rapid erosion of drainage spillways around the edge of Glacial Lake Duluth released tremendous amounts of water in a short time. These torrents of meltwater readily cut through the glacial sediments and the sandstone, deepening the St. Croix valley. Fierce rapids developed where the rushing current encountered the hard, resistant basalt. The rapids increased the speed and turbulence of the water, and a heavy sediment load provided powerful abrasive action—all necessary to carve potholes into the basalt.

Potholes commonly occur behind the base of a large boulder or other flow obstruction. They are made when turbulent water forms an eddy, or whirlpool, strong enough to swirl pebbles and cobbles around in one spot. There the swirling stones grind a cylindrical hole down into the bedrock. The exceptional depth and abundance of potholes here attest to the enormous power of Glacial River St. Croix.

Erected by the Geological Society of Minnesota in partnership with the Minnesota Department of Transportation, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources. 2003

Region: Metro Region

Date Updated: 20170414

Information Needed:

  1. Marker Images

Condition of Marker: Good
Do it Yourself Region: St. Croix River Valley
Verification: Bennyonbeacon@comcast.net

Title: Glacial Potholes
Road Markers

Description:

Minnesota Potholes. 

Google Map panorama image of the Pothole.

The St. Croix Dalles (Home of the World’s Deepest Potholes)

More Info.

 

Enter Road Address in your cars GPS:
307 Milltown Rd, Taylors Falls, MN 55084

OR

Enter Geographical Coordinates in your cars GPS:

Degrees Lat Long:   45.399417, -92.651556

Latitude:      45°23’57.9″N
Longitude:   92°39’05.6″W

Go to Google Map

Country: Chisago County

Where Found:

 Marker is in Taylors Falls, Minnesota, in Chisago County. Marker can be reached from U.S. 8 near Bench Street. Marker is in Interstate State Park (vehicle permit required) beyond the Visitor Center.

Marker Number: 4

Marker Composition: Stone with Bronze plaques

Text on Marker:

Glacial Potholes

The potholes at the St. Croix Dalles have their origins in a tale of fire and ice. They are carved in a dark volcanic rock called basalt, which erupted as lava 1.1 billion years ago. This basalt is related to lava flows that line the North Shore of Lake Superior. About 500 million years ago, when shallow tropical seas covered this area, the basalt was buried beneath a thick blanket of sand, which later became sandstone.

During the last two million years, glaciers have advanced from the Ontario region through the Lake Superior basin, repeatedly covering the Taylors Falls area. About 12,000 years ago, near the end of the most recent glaciation, meltwater collected at the southwestern edge of a glacial lobe as the lobe receded into the Superior basin. This water formed a growing Glacial Lake Duluth. When Glacial Lake Duluth drained, great floods flowed southward through the St. Croix River valley, forming Glacial River St. Croix. The largest of these floods was perhaps a hundred times the volume of modern ones. At this time, Glacial Lake Duluth drained only via Glacial River St. Croix, because ice still blocked the Superior basin’s eastern outlet to the lower Great Lakes.

Rapid erosion of drainage spillways around the edge of Glacial Lake Duluth released tremendous amounts of water in a short time. These torrents of meltwater readily cut through the glacial sediments and the sandstone, deepening the St. Croix valley. Fierce rapids developed where the rushing current encountered the hard, resistant basalt. The rapids increased the speed and turbulence of the water, and a heavy sediment load provided powerful abrasive action—all necessary to carve potholes into the basalt.

Potholes commonly occur behind the base of a large boulder or other flow obstruction. They are made when turbulent water forms an eddy, or whirlpool, strong enough to swirl pebbles and cobbles around in one spot. There the swirling stones grind a cylindrical hole down into the bedrock. The exceptional depth and abundance of potholes here attest to the enormous power of Glacial River St. Croix.

Erected by the Geological Society of Minnesota in partnership with the Minnesota Department of Transportation, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources. 2003

Region: Metro Region

Date Updated: 20170414 Information Needed:

  1. Marker Images

Condition of Marker: Good

Do it Yourself Region: St. Croix River Valley

Verification: Bennyonbeacon@comcast.net

Title: Glacial Potholes
Road Markers

Description:

Minnesota Potholes. 

Google Map panorama image of the Pothole.

The St. Croix Dalles (Home of the World’s Deepest Potholes)

More Info.

 

Enter Road Address in your cars GPS:
307 Milltown Rd, Taylors Falls, MN 55084

OR

Enter Geographical Coordinates in your cars GPS:

Degrees Lat Long:   45.399417, -92.651556

Latitude:      45°23’57.9″N
Longitude:   92°39’05.6″W

Go to Google Map

Country: Chisago County

Where Found:

 Marker is in Taylors Falls, Minnesota, in Chisago County. Marker can be reached from U.S. 8 near Bench Street. Marker is in Interstate State Park (vehicle permit required) beyond the Visitor Center.

Marker Number: 4

Marker Composition: Stone with Bronze plaques

Text on Marker:

Glacial Potholes

The potholes at the St. Croix Dalles have their origins in a tale of fire and ice. They are carved in a dark volcanic rock called basalt, which erupted as lava 1.1 billion years ago. This basalt is related to lava flows that line the North Shore of Lake Superior. About 500 million years ago, when shallow tropical seas covered this area, the basalt was buried beneath a thick blanket of sand, which later became sandstone.

During the last two million years, glaciers have advanced from the Ontario region through the Lake Superior basin, repeatedly covering the Taylors Falls area. About 12,000 years ago, near the end of the most recent glaciation, meltwater collected at the southwestern edge of a glacial lobe as the lobe receded into the Superior basin. This water formed a growing Glacial Lake Duluth. When Glacial Lake Duluth drained, great floods flowed southward through the St. Croix River valley, forming Glacial River St. Croix. The largest of these floods was perhaps a hundred times the volume of modern ones. At this time, Glacial Lake Duluth drained only via Glacial River St. Croix, because ice still blocked the Superior basin’s eastern outlet to the lower Great Lakes.

Rapid erosion of drainage spillways around the edge of Glacial Lake Duluth released tremendous amounts of water in a short time. These torrents of meltwater readily cut through the glacial sediments and the sandstone, deepening the St. Croix valley. Fierce rapids developed where the rushing current encountered the hard, resistant basalt. The rapids increased the speed and turbulence of the water, and a heavy sediment load provided powerful abrasive action—all necessary to carve potholes into the basalt.

Potholes commonly occur behind the base of a large boulder or other flow obstruction. They are made when turbulent water forms an eddy, or whirlpool, strong enough to swirl pebbles and cobbles around in one spot. There the swirling stones grind a cylindrical hole down into the bedrock. The exceptional depth and abundance of potholes here attest to the enormous power of Glacial River St. Croix.

Erected by the Geological Society of Minnesota in partnership with the Minnesota Department of Transportation, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources. 2003

Region: Metro Region

Date Updated: 20170414 Information Needed:

  1. Marker Images

Condition of Marker: Good

Do it Yourself Region: St. Croix River Valley

Verification: Bennyonbeacon@comcast.net

Title: Glacial Potholes
Road Markers

Description:

Minnesota Potholes. 

Google Map panorama image of the Pothole.

The St. Croix Dalles (Home of the World’s Deepest Potholes)

More Info.

 

Enter Road Address in your cars GPS:
307 Milltown Rd, Taylors Falls, MN 55084

OR

Enter Geographical Coordinates in your cars GPS:

Degrees Lat Long:   45.399417, -92.651556

Latitude:      45°23’57.9″N
Longitude:   92°39’05.6″W

Go to Google Map

Country: Chisago County

Where Found:

 Marker is in Taylors Falls, Minnesota, in Chisago County. Marker can be reached from U.S. 8 near Bench Street. Marker is in Interstate State Park (vehicle permit required) beyond the Visitor Center.

Marker Number: 4

Marker Composition: Stone with Bronze plaques

Text on Marker:

Glacial Potholes

The potholes at the St. Croix Dalles have their origins in a tale of fire and ice. They are carved in a dark volcanic rock called basalt, which erupted as lava 1.1 billion years ago. This basalt is related to lava flows that line the North Shore of Lake Superior. About 500 million years ago, when shallow tropical seas covered this area, the basalt was buried beneath a thick blanket of sand, which later became sandstone.

During the last two million years, glaciers have advanced from the Ontario region through the Lake Superior basin, repeatedly covering the Taylors Falls area. About 12,000 years ago, near the end of the most recent glaciation, meltwater collected at the southwestern edge of a glacial lobe as the lobe receded into the Superior basin. This water formed a growing Glacial Lake Duluth. When Glacial Lake Duluth drained, great floods flowed southward through the St. Croix River valley, forming Glacial River St. Croix. The largest of these floods was perhaps a hundred times the volume of modern ones. At this time, Glacial Lake Duluth drained only via Glacial River St. Croix, because ice still blocked the Superior basin’s eastern outlet to the lower Great Lakes.

Rapid erosion of drainage spillways around the edge of Glacial Lake Duluth released tremendous amounts of water in a short time. These torrents of meltwater readily cut through the glacial sediments and the sandstone, deepening the St. Croix valley. Fierce rapids developed where the rushing current encountered the hard, resistant basalt. The rapids increased the speed and turbulence of the water, and a heavy sediment load provided powerful abrasive action—all necessary to carve potholes into the basalt.

Potholes commonly occur behind the base of a large boulder or other flow obstruction. They are made when turbulent water forms an eddy, or whirlpool, strong enough to swirl pebbles and cobbles around in one spot. There the swirling stones grind a cylindrical hole down into the bedrock. The exceptional depth and abundance of potholes here attest to the enormous power of Glacial River St. Croix.

Erected by the Geological Society of Minnesota in partnership with the Minnesota Department of Transportation, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources. 2003

Region: Metro Region

Date Updated: 20170414 Information Needed:

  1. Marker Images

Condition of Marker: Good

Do it Yourself Region: St. Croix River Valley

Verification: Bennyonbeacon@comcast.net

Title: Glacial Potholes
Road Markers

Description:

Minnesota Potholes. 

Google Map panorama image of the Pothole.

The St. Croix Dalles (Home of the World’s Deepest Potholes)

More Info.

 

Enter Road Address in your cars GPS:
307 Milltown Rd, Taylors Falls, MN 55084

OR

Enter Geographical Coordinates in your cars GPS:

Degrees Lat Long:   45.399417, -92.651556

Latitude:      45°23’57.9″N
Longitude:   92°39’05.6″W

Go to Google Map

Country: Chisago County

Where Found:

 Marker is in Taylors Falls, Minnesota, in Chisago County. Marker can be reached from U.S. 8 near Bench Street. Marker is in Interstate State Park (vehicle permit required) beyond the Visitor Center.

Marker Number: 4

Marker Composition: Stone with Bronze plaques

Text on Marker:

Glacial Potholes

The potholes at the St. Croix Dalles have their origins in a tale of fire and ice. They are carved in a dark volcanic rock called basalt, which erupted as lava 1.1 billion years ago. This basalt is related to lava flows that line the North Shore of Lake Superior. About 500 million years ago, when shallow tropical seas covered this area, the basalt was buried beneath a thick blanket of sand, which later became sandstone.

During the last two million years, glaciers have advanced from the Ontario region through the Lake Superior basin, repeatedly covering the Taylors Falls area. About 12,000 years ago, near the end of the most recent glaciation, meltwater collected at the southwestern edge of a glacial lobe as the lobe receded into the Superior basin. This water formed a growing Glacial Lake Duluth. When Glacial Lake Duluth drained, great floods flowed southward through the St. Croix River valley, forming Glacial River St. Croix. The largest of these floods was perhaps a hundred times the volume of modern ones. At this time, Glacial Lake Duluth drained only via Glacial River St. Croix, because ice still blocked the Superior basin’s eastern outlet to the lower Great Lakes.

Rapid erosion of drainage spillways around the edge of Glacial Lake Duluth released tremendous amounts of water in a short time. These torrents of meltwater readily cut through the glacial sediments and the sandstone, deepening the St. Croix valley. Fierce rapids developed where the rushing current encountered the hard, resistant basalt. The rapids increased the speed and turbulence of the water, and a heavy sediment load provided powerful abrasive action—all necessary to carve potholes into the basalt.

Potholes commonly occur behind the base of a large boulder or other flow obstruction. They are made when turbulent water forms an eddy, or whirlpool, strong enough to swirl pebbles and cobbles around in one spot. There the swirling stones grind a cylindrical hole down into the bedrock. The exceptional depth and abundance of potholes here attest to the enormous power of Glacial River St. Croix.

Erected by the Geological Society of Minnesota in partnership with the Minnesota Department of Transportation, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources. 2003

Region: Metro Region

Date Updated: 20170414 Information Needed:

  1. Marker Images

Condition of Marker: Good

Do it Yourself Region: St. Croix River Valley

Verification: Bennyonbeacon@comcast.net

Title: Glacial Potholes
Road Markers

Description:

Minnesota Potholes. 

Google Map panorama image of the Pothole.

The St. Croix Dalles (Home of the World’s Deepest Potholes)

More Info.

 

Enter Road Address in your cars GPS:
307 Milltown Rd, Taylors Falls, MN 55084

OR

Enter Geographical Coordinates in your cars GPS:

Degrees Lat Long:   45.399417, -92.651556

Latitude:      45°23’57.9″N
Longitude:   92°39’05.6″W

Go to Google Map

Country: Chisago County

Where Found:

 Marker is in Taylors Falls, Minnesota, in Chisago County. Marker can be reached from U.S. 8 near Bench Street. Marker is in Interstate State Park (vehicle permit required) beyond the Visitor Center.

Marker Number: 4

Marker Composition: Stone with Bronze plaques

Text on Marker:

Glacial Potholes

The potholes at the St. Croix Dalles have their origins in a tale of fire and ice. They are carved in a dark volcanic rock called basalt, which erupted as lava 1.1 billion years ago. This basalt is related to lava flows that line the North Shore of Lake Superior. About 500 million years ago, when shallow tropical seas covered this area, the basalt was buried beneath a thick blanket of sand, which later became sandstone.

During the last two million years, glaciers have advanced from the Ontario region through the Lake Superior basin, repeatedly covering the Taylors Falls area. About 12,000 years ago, near the end of the most recent glaciation, meltwater collected at the southwestern edge of a glacial lobe as the lobe receded into the Superior basin. This water formed a growing Glacial Lake Duluth. When Glacial Lake Duluth drained, great floods flowed southward through the St. Croix River valley, forming Glacial River St. Croix. The largest of these floods was perhaps a hundred times the volume of modern ones. At this time, Glacial Lake Duluth drained only via Glacial River St. Croix, because ice still blocked the Superior basin’s eastern outlet to the lower Great Lakes.

Rapid erosion of drainage spillways around the edge of Glacial Lake Duluth released tremendous amounts of water in a short time. These torrents of meltwater readily cut through the glacial sediments and the sandstone, deepening the St. Croix valley. Fierce rapids developed where the rushing current encountered the hard, resistant basalt. The rapids increased the speed and turbulence of the water, and a heavy sediment load provided powerful abrasive action—all necessary to carve potholes into the basalt.

Potholes commonly occur behind the base of a large boulder or other flow obstruction. They are made when turbulent water forms an eddy, or whirlpool, strong enough to swirl pebbles and cobbles around in one spot. There the swirling stones grind a cylindrical hole down into the bedrock. The exceptional depth and abundance of potholes here attest to the enormous power of Glacial River St. Croix.

Erected by the Geological Society of Minnesota in partnership with the Minnesota Department of Transportation, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources. 2003

Region: Metro Region

Date Updated: 20170414 Information Needed:

  1. Marker Images

Condition of Marker: Good

Do it Yourself Region: St. Croix River Valley

Verification: Bennyonbeacon@comcast.net

Members


  • Member Information
  • – Seminars and labs
  • Seminar/Lab Calendar
  • Current Year Schedule
  • All Seminar and Lab
  • Direction to Seminars and Labs
  • Field Trips
  • Field Trip Calendar
  • Upcoming Field Trips
  • Past Field Trips
  • Waiver of Liability
  • Waiver of Liability PDF
  • Video Library
  • GSM Video Library Display
  • Suggested YouTube Videos
  • GSM T Shirts and Caps
  • Add Clothing Item
  • Newsletter
  • Display Newsletters
  • Contribute to Newsletters
  • Board
  • Display Board Minutes
  • Board Information
  • Presidents of the GSM

Link/Outreach/About


  • Link
  • Outreach
  • For Teacher
  • State Fair
  • State Fair Booth Rock Specimens List
  • About
  • History
  • Organization Information
  • Articles of Incorporation
  • By Laws
  • Mission
  • Administrator Login

Contact/Display Post/ Road Markers


  • Contact
  • Ask GSM
  • Ask ChatGPT a geology question
  • GSM USPS Mailing Address
  • Post/Blog
  • Display Post
  • Display Post List
  • Road Markers
Facebook X Instagram

© 2025 Geological Society of Minnesota - WordPress Theme by Kadence WP

  • Welcome Page
  • Road Markers
  • Members
    • Seminars and Labs
      • Seminar/Lab Calendar
      • Current Year Schedule
      • All Seminars and Labs
      • Directions to Seminars and Labs
    • Fields Trips
      • Field Trip Calendar
      • Help Field Trip Signup
      • Upcoming Field Trip
      • Field Trips Signup
      • Submit Field Trip Suggestions
      • Past Field Trips
      • Waiver of Liability
      • Waiver of Liability PDF
    • Calendars
      • Seminar/Lab Calendar
      • Field Trip Calendar
    • Member Information
      • Print a Membership Form
      • Enter in your membership form, then print
      • Membership application/renewal via credit card
      • Membership Help Document
    • Media Library
      • Media Library Order/Display
      • Help Using Media Library
      • Suggested Geology YouTube Videos
    • GMS T Shirts and Caps
      • Buy T Shirt and/or Cap
      • Help buying T Shirt/Cap
    • Newsletters
      • Display Newsletters
      • NLs from the MN Geological Survey
        • Newsletter JPG Large
        • Newsletter JPG Small
      • Contributing to the Newsletter
  • Link
  • Outreach
    • For Teacher
    • State Fair
      • State Fair Booth Rock Specimens List
  • About
    • History
    • Board
      • Display Board Minutes
      • Board Information
      • GSM presidents
    • Organization Information
      • Articles of Incorporation
      • By_Laws
    • Mission
    • Administrator Login
      • Administrator Login Help
  • Contact
    • Ask GSM
    • Ask ChatGPT a geology question
    • GSM USPS mailing address
  • Display Posts
    • Display Blog Posts List
    • Display Blog Posts by Category
    • Help Viewing Blog Posts