This image shows visitors scanning the Lake Superior shoreline for collectible rocks near the town of Two Harbors, Minnesota.
The description states:
Rockhounds search the North Shore of Lake Superior for its many gemstones. Here agates may be found by the handful.
–Rock collecting has become less popular as time has passed and laws against collecting in most parks and public lands have been passed.
This card was used and is dates 24 August 1964.