Visiting an Earthcache in a National Park is more than just "Logging A Find", it is an Earth Science Lesson that we hope you will enjoy.

Pictured Rocks National Lakeshore isAmerica's first National Lakeshore, established by the 89th Congress of the United States on October 15, 1966. There are opportunities for many recreational activities thanks to the development of trails, campgrounds and roads in and around the Lakeshore’s boundaries. Pictured Rocks National Lakeshore has two gateways – Grand Marais at the eastern edge and Munising at the west. Sleeping Bear Dunes, The Apostle Islands and Indiana Dunes are the three other national lakeshores that were authorized in subsequent years.

Permission for this Earthcache was granted by the Pictured Rocks National Lake Shore Park Service because of Earthcache’s Leave No Trace principles, and the fact there is no placement of any physical cache container. Having a cache container placed anywhere within any National Park Service boundaries is strictly prohibited. Munising Falls, Grand Sable Dunes – A Perched Dune, Miners Castle Sea Cave, Pictured Rocks from Lake Superior, Miners Castle, Miners Falls and Pictured Rocks View Earth Cache are the other earthcaches currently available at the Lakeshore.
Geological history recorded in the sedimentary rocks and surficial deposits of Pictured Rocks National Lakeshore is limited to two widely separated intervals of geologic time, the Late Precambrian, Cambrian, and Early Ordovician Periods (500-800 million years before present) and the Late Quaternary Period (two million years before present to the present).

During the Cambrian and Early Ordovician periods, sediments were deposited in the shallow seas and near-shore deltas that covered what is now northern Michigan. These deposits became the sandstone units that are exposed within the Lakeshore. Except for their exposure near Lake Superior, these units are presently covered by a veneer of Quaternary glacial drift.

Bedrock is best observed in the western one-third of the Lakeshore where cliffs rise up to 180 feet from Lake Superior. These extend along the lake about 17 miles from Munising to Beaver Basin. For a short distance inland from the escarpment, bedrock is occasionally exposed.

Geologists originally thought four North American glacial stages advanced and retreated through the area during the Pleistocene epoch. However, more recent research indicates up to 24 major glaciations occurred. (Pictured Rocks Resource Report by William L. Blewett, Shippensburg University of Pennsylvania) A brief re-advance of ice occurred 10,000 years ago in northern Upper Michigan. Melting of glacial ice within the Superior Basin produced huge rivers that deposited millions of tons of pulverized rock rubble in various configurations to the south of the Superior basin. A sheet of outwash, of varying thickness, was deposited along the south edge of Pictured Rocks National Lakeshore. Meltwater carved several channels into Cambrian sandstone bedrock.

The rivers and streams that flow to Lake Superior through Pictured Rocks National Lakeshore have a relatively steep gradient and are rather short, because the peninsular divide in the area is much closer to Lake Superior than to Lake Michigan. The steep gradient includes waterfalls, where the streams drop over the escarpment. Rivers flowing within the Pictured Rocks National Lakeshore have created seven named waterfalls plus several unnamed falls. From west to east, they are Munising, Bridalveil, Miners, Mosquito, Chapel, Spray, and Sable Falls. The sandstone outcrops of the Pictured Rocks escarpment create the many waterfalls in the area. One such river is Miners River.

Miners River has its origin outside of the National Lakeshore, near Ginpole Lake in the Hiawatha National Forest, and flows for over 8 miles into Lake Superior. Miners River is the longest and largest river in the lakeshore. Its discharge near the mouth averages 46 cubic feet per second during June and drops to an average of 21 cubic feet per second in late summer and fall. Its route includes Miners Lake and Miners Falls. Miners Lake is a 10 hectare lake that is a spawning habitat for native fish species such as Lake Trout. The substrates of the streams are variously composed of cobble/gravel, sand, and bedrock. The substrate in depositional areas along the banks and upstream from beaver dams is mud/silt. Most pools are formed by the force of water flowing over trees that have fallen into the streams. The river’s bottom can be inspected as you walk upstream from Miners Beach. The river empties into Lake Superior at the western end of Miners Beach. The glaciers and meltwater that carved the Miners River functional, yet beautiful, marvel of nature.

There are three requirements for logging the Miners River EarthCache.

1. Post two pictures in your log with your gpsr visible. The first should be at the posted coordinates with the informational sign visible. The second picture should be taken at Miners Beach with Miners River in the background. I suggest going to N 46° 29.698 W 086° 32.888.

2. Using your gpsr take elevation readings at both sets of posted coordinates. Email me the elevations. BONUS: If you are completing the one and only Lost Scouts Miners Falls EarthCache, take an elevation reading and include it in your email.

3. As you look up river from the beach, what is your estimate of the widest portion of the river? How does it compare to the width of the river where it discharges into Lake Superior? Include this information in your email.

Did You Know?
In 1992, the Pictured Rocks National Lakeshore began installing photovoltaic powered well pump systems at its drive-in campgrounds. All remote water wells within the lakeshore are now solar-powered.