Unveiling the Secrets of Michigan’s Sandstone Masterpiece
The colorful sandstone cliffs of Pictured Rocks National Lakeshore tower 50 to 200 feet above Lake Superior. These sandstone cliffs stretch for about 15 miles along Lake Superior from Sand Point on the west to just after Spray Falls on the east. The most colorful portion of the cliffs begin east of Miners Beach.
The oldest rocks visible above water in Pictured Rocks National Lakeshore were deposited between 500 million to 1 billion years ago. The core of the North American continent began to split apart 1.1 billion years ago, forming the Midcontinent Rift System. The rift failed approximately 15-20 million years after the beginning of its formation, but not before leaving a basin now filled by Lake Superior. Over time, the sand and gravel lithified, forming the Jacobsville Formation, a terrestrial rock unit. The iron oxide in this formation imparts a characteristic red color. Only the very top of the formation is exposed above the water.
The name “Pictured Rocks” comes from streaks of mineral stain that decorate the face of the weather-sculpted sandstone. Stunning colors occur when groundwater seeps out of cracks and trickles down the rock face. Iron (red and orange), copper (blue and green), manganese (brown and black), and limonite (white) are among the most common color-producing minerals.
Changing Appearances of Pictured Rocks
Grand Portal is one of the most impressive features of the Pictured Rocks. A wide archway once opened into a cave so large that boats could pass through it, but the roof of the cavern collapsed in 1906. Gradual changes can be seen in the Grand Portal. Its huge arch formation continues to erode causing the sandstone to fill in the archway below.
Pictured Rocks Cruises offers you a unique experience to view the many caverns, captivating rock walls and formations, suspended archway, and the massive rock face.
Sometimes changes happen overnight. Miners Castle is probably the most recognizable formation of the Pictured Rocks and on 4/13/06 it lost one of its two towers or “turrets”. The appearance of the castle changed immensely after the turret fell into Lake Superior. Rockfalls along the cliffs typically occur in the spring and fall due to the freezing and thawing action of Mother Nature.
You can get close up views of Miners Castle with Pictured Rocks Kayaking while exploring beautiful colors and caves by water.
Visitors flock to Picture Rocks National Lakeshore every summer to take in the unparalleled formations of these majestic wonders. In Munising, the western gateway community to the park, you can take a narrated boat tour that includes all of the highlights of this awe-inspiring area. Pictured Rocks Cruises offers passengers stunning views of the colorful cliffs and sea caves that are stained by lake minerals, waterfalls, and other iconic landmarks.
Pictured Rocks Kayaking tours are the only excursions along the Pictured Rocks National Lakeshore that are both guided kayak tour and boat tour in one! Sit back and relax as we take you to the best parts of the lakeshore.
Experience the marvel of the Pictured Rocks National Lakeshore in Munising!