#Nature

These formations are part of the Anastasia Formation, dating back to the Late Pleistocene Epoch, when powerful coastal forces shaped this region’s geology.

The coquina at Washington Oaks formed in a high-energy beach environment, where constant wave action broke down shells and compacted them into a porous, durable stone.

Though relatively soft when first formed, coquina hardens over time, which is why the outcroppings along the park’s shoreline have resisted erosion and remain exposed today.

These weathered formations create shallow tidal pools that support crabs, sea snails, and small marine life.

Because large coquina outcroppings are rare on Florida’s Atlantic coast, the beach at Washington Oaks is both geologically significant and visually dramatic. It's a protected area, so visitors are asked not to disturb or collect the rock.

Learn more at the Florida State Parks website.

The striations are vertical bands of lighter-colored rock that slice through the darker granite and gneiss that make up much of the canyon walls. These striations are particularly visible along the Painted Wall, the tallest cliff in Colorado, standing at about 2,250 feet. The contrast between the dark base rock and the lighter striations creates a striking visual effect, reminiscent of brushstrokes on a massive canvas.

The striations of Black Canyon are unique due to their composition and formation process. The bands are composed primarily of pegmatite, a type of igneous rock that is lighter in color and coarser-grained than the surrounding dark granite and gneiss. Pegmatite forms when molten rock cools slowly deep underground, allowing larger crystals to develop. The resulting bands appear lighter and more reflective, standing out distinctly against the darker rock.

Formation

The formation of the striations is a story that dates back over 1.7 billion years. The base rock of Black Canyon is some of the oldest exposed rock in North America. Over eons, tectonic activity caused magma to push up into cracks within the pre-existing granite and gneiss. As the magma cooled and solidified, it formed the pegmatite intrusions that now streak down the walls of the canyon.

Over time, the region was uplifted by geological forces, exposing these ancient formations to the surface. The Gunnison River then took over, carving the canyon through relentless erosion over approximately two million years. The river's power combined with the harder, more erosion-resistant pegmatite left behind the dramatic striations, contrasting with the smoother erosion of the surrounding rock.

For more, checkout the official Black Canyon of the Gunnison National Park website.