# Ontario is Getting Taller

Source: https://www.youtube.com/watch?v=_8Lk9YeovbE
Recap page: https://rapidrecap.app/video/_8Lk9YeovbE
Generated: 2026-07-23T14:12:18.452+00:00

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## The Gist

The title promises to explain how Ontario is getting taller. The real answer is that ancient glaciers depressed the Earth's crust, and now that the ice is gone, the land is rebounding upward by 13 millimeters every year.

## Quick Overview

Ontario is rising in elevation because of glacial isostatic rebound, a process where the Earth's crust springs back upward after the immense weight of the Laurentide Ice Sheet melts away. Ancient glaciers shaped the geography of North America and Europe by carving deep fjords, leaving behind massive beds of glacial till, depositing giant erratic boulders, and carving the Great Lakes. While Ontario rises, other regions like coastal areas and parts of the British Isles continue to sink as surrounding forebulges relax.

**Key Points:**
- About 27,000 years ago, ice sheets covered Canada, the United States, Iceland, and Scandinavia, fundamentally carving and changing the geology of the northern hemisphere.
- Fjords in Norway formed as ancient glaciers flowed down mountain valleys and carved steep U-shaped channels, leaving behind submerged valleys that plunge deep below sea level.
- Glacial till left behind by the Laurentide Ice Sheet created flat and fertile soil across the American Midwest rich in nutrients like phosphorus, potassium, and zinc.
- Large boulders called erratics were carried hundreds of kilometers away from their origins by glaciers and dropped in new locations, such as Waldo's Rock in Iowa.
- The Great Lakes and other water basins were carved out by the sheer weight of the Laurentide Ice Sheet and filled with meltwater when the ice retreated.
- Glacial isostatic rebound causes parts of Ontario, Canada, to rise by 13 millimeters every year as the land springs back from the weight of former ice sheets.
- The Driftless Area in Wisconsin escaped glacial coverage entirely because the high-elevation terrain forced the ice sheet to flow around it, leaving behind steep rocky bluffs.

![Screenshot at 08:48: A geological map highlighting Ontario, Canada, getting taller by 13 millimeters per year due to glacial isostatic rebound.](https://ss.rapidrecap.app/screens/_8Lk9YeovbE/00-08-48.jpg)

**Context:** Glaciers have repeatedly advanced and retreated across North America and Europe, leaving behind a scarred and sculpted landscape that dictates modern agriculture, water systems, and topography. Understanding these ancient ice sheets explains why certain regions are flat, why massive boulders sit in random forests, and why the Earth's crust is still moving today.

## Detailed Analysis

Ancient ice sheets carved the geography of the northern hemisphere, leaving enduring geological features across North America and Europe. Glaciers carved steep U-shaped valleys that became fjords in Norway, ground up bedrock into nutrient-rich glacial till that turned the American Midwest into an agricultural powerhouse, and deposited erratic boulders far from their native origins. The immense weight of the Laurentide Ice Sheet carved the basins of the Great Lakes and depressed the Earth's crust. Now that the ice has melted, the land is undergoing glacial isostatic rebound, causing regions like Ontario to rise by 13 millimeters every year while former forebulge areas slowly sink.

### #1, Fjords of Norway

Fjords are long, narrow channels of water bordered by towering near-vertical cliffs shaped by ancient rivers of ice.

- Glaciers flowing down mountain peaks followed the path of least resistance through pre-carved river valleys.
- As glaciers moved, they swallowed rocks and pressed them against the ground, chewing up the landscape and carving out deep V-shaped valleys into U-shaped fjords.
- When the glaciers eventually melted, their water and sunken U-shaped bottoms became submerged, leaving tall cliff sides towering above the sea.

![Screenshot at 00:53: An aerial view of a narrow Norwegian fjord surrounded by steep green cliffs and blue water.](https://ss.rapidrecap.app/screens/_8Lk9YeovbE/00-00-53.jpg)

### #2, The Flat and Fertile American Midwest

The American Midwest is known for its endless flatness and rich agricultural output, both of which trace back to glacial activity.

- The Laurentide Ice Sheet blanketed the Midwest, smoothing and eroding the terrain as it spread across the land.
- When the ice sheet retreated, it left behind glacial till layers more than 30 meters deep in some places.
- Glacial till is rich in phosphorus, potassium, zinc, and selenium, which improves crop yields and makes the Midwest an agricultural powerhouse.

![Screenshot at 02:41: An aerial shot of flat agricultural fields spanning the American Midwest.](https://ss.rapidrecap.app/screens/_8Lk9YeovbE/00-02-41.jpg)

### #3, Great Lakes

The Great Lakes and countless smaller water basins are direct products of glacial excavation and meltwater trapping.

- The Laurentide Ice Sheet was up to three kilometers thick in places and covered everything from the North Pole to Pennsylvania.
- The sheer weight of the ice sheet carved out massive basins that flooded with meltwater as the climate warmed.
- Glacial retreat also formed paternoster lakes, which are strings of small lakes separated by moraines that resemble beads on a rosary.

![Screenshot at 06:05: A satellite view of the Great Lakes basin system carved by ancient glaciers.](https://ss.rapidrecap.app/screens/_8Lk9YeovbE/00-06-05.jpg)

### #4, Ontario is Getting Taller

Planetary-scale isostatic rebound is actively changing elevations across North America and Europe.

- The Earth's crust acts like a giant trampoline, bending downward under the massive weight of ice sheets over thousands of years.
- When the ice melts, the ground slowly springs back upward in a process called glacial isostatic rebound.
- Ontario, Canada, is rising by 13 millimeters every year because it sat directly underneath the center of the former Laurentide ice sheet.

![Screenshot at 08:31: A scenic coastal view illustrating the changing shorelines caused by ongoing glacial rebound.](https://ss.rapidrecap.app/screens/_8Lk9YeovbE/00-08-31.jpg)

### #5, Suspiciously Absent Features

Some unique landscapes exist precisely because ancient glaciers completely missed them.

- The Driftless Area in Wisconsin is a pocket of steep rocky bluffs and deep valleys that the ice sheet flowed around.
- Because the Driftless Area sat above the ice, it missed out on glacial drift and was never eroded flat.
- The Channeled Scablands in Washington state were formed when a natural ice dam holding back Glacial Lake Missoula repeatedly broke, unleashing catastrophic floods that reshaped the terrain.

![Screenshot at 10:11: A map outline highlighting the unglaciated Driftless Area in Wisconsin.](https://ss.rapidrecap.app/screens/_8Lk9YeovbE/00-10-11.jpg)