Glacier Garden Lucerne

The glacier garden was uncovered by chance on November 2nd, 1872, by Josef Wilhelm Amrien-Troller while building a wine cellar on the site. The natural monument was opened to the public on May 1st, 1873, while excavation work continued until 1876.
The glaciers that polished the rocks and created these potholes covered Switzerland about 20,000 years ago. The parallel grooves running from north to south indicate the direction the glacier was flowing. The glacial striation marks were scoured by the rocks trapped inside the ice, which flowed several centimeters per day.

The rocks either fell onto the glacier surface in the Alps or where scooped up from the ground by the ice and transported down into the valley. The boulders provide evidence that the alpine foreland was once almost entirely covered by glaciers. The ice covering Lucerne was almost 1,000 meters thick.

This pothole is 9.5 meters deep and is 8 meters in diameter.

The potholes were formed at the bottom of the glacier by the sheer force of water. Pictured above is the largest of the potholes in the glacier garden. To provide some perspective:

Keith standing by the glacier pothole.

Meg standing near the largest pothole in the glacier garden.

How these potholes are made:
The melted water initially flows on the surface of the ice before seeping into the glacier through fissures. At the bottom of the glacier the water is under tremendous pressure. As the flow of water gathers speed, vortexes with speeds up to 200 km/hour begin to form. Within a few years, potholes are eroded out of the rock. Most of the erosion is created by sand and gravey that was transported with the water.



Below is a video of a model of how the potholes were formed: