If you follow the Marr Lake Trail in Bruce Peninsula National Park you will reach the Boulder Beach with unusual landscape. This beach is covered mostly with rounded rocks and there is no vegetation in this area.
This landscape is formed by the shape of the shore line and the seasonal lake ice activity. Shoreline has bottle neck shape with two strong limestone sides. When the ice starts breaking in Georgian bay, strong wind pushes all the ice into the bottleneck. It's called ice shove or ice push. It's the movement, offshore or shoreward, of rock fragments over the bedrock surface by ice. Rock fragments are either scattered on the platform or concentrated in shallow depressions and along small scarps. They may also form large block ridges in the high storm events.
In order to log this earthcache as found you have to answer following questions:
- What kind of rocks mostly can be found in this area and what other kinds of rocks you can find here? Why?
- Measure the elevation at the highest point of the beach and at two provided reference points. How high is the Boulder Beach?
- What the difference in elevation between the Lake water and the Marr Lake? Do you think Marr Lake was a part of the Georgian bay before stone ridge been formed?