THE PICTURED ROCKS AT MUNISING, MICHIGAN.
The geological history of the Pictured Rocks began between 500 and 600 million years ago, during the Cambrian and early Ordovician periods. At this time, shallow seas and sediment deposits, which became the sandstone units that are now called the Pictured Rocks, covered what is now Northern Michigan.
Bedrock is exposed for a distance of about 15 miles east of Munising. This exposure was caused by two important items. One: During the glacial age, Lake Superior was some 40 or 50 feet higher than it is today. As the glaciers began to recede farther north, the lake, called Nippising by the Indians, broke through on its eastern end and lowered to its present level. Two: At this time, the great weight of the glaciers was now gone from the land, which now rose. This combination of glaciers receding, land rising and the lake lowering, caused much of what is viewed along the Pictured Rocks. Wave action, wind and other weather conditions, caused erosion and has left them as we see them today.
The Pictured Rocks escarpment has been carved by frost and wave action of the present lake into a variety of shore cliff features such as stacks, caves, sea arches, thunder caves and promontories, which are especially when boating past them on the lake.
Pictured Rocks sounds like a misnomer. One visualizes “pictures” as painted by hand. This is not the case. The name “Pictured Rocks” is lost in antiquity. Perhaps it was named by the Indians some centuries ago. Perhaps, too, it was named by Longfellow in his poem “Hiawatha”. That was the first time it appeared in print. In the 1700’s French explorers named some of the rocks, and they had gotten the names from the Indians.
Wherever the name came from, one cannot deny its descriptiveness of the incredible view one sees along the escarpments that are known as Pictured Rocks.