As you explore the coastline here in Yachats and in the Cape Perpetua Scenic Area south to Heceta Head, one thing is noticeable: the dark, shelf-like rock formations that meet the ocean’s crashing waves. This rock, in general, is basalt. More specifically, it is Yachats Basalt, formed in the Eocene Era about 37 million years ago. Basalt is solidified lava. And where there’s basalt, there is evidence of previous volcanic action.
So, was there a volcano in the Yachats area? According to retired geologist David Meurdter, who gives regular geologic talks through the Cape Perpetua Collaborative, yes!
About 37 million years ago, although the Oregon coastline looked different than it does today, the Siletzia terrane was in place below ground, Meurdter explains. A terrane is a fault-bounded block that collides with the continent and attaches. The volcano was at the edge of this terrane as part of an offshore island. Over time, most of the volcano eroded thanks to constant wave action, creating the capes and headlands we admire. Devil’s Churn, Cook’s Chasm, Thor’s Well – these and more have formed because of wave action and in some cases earthquake action to widen cracks and open up holes, creating dramatic features that draw our attention.
Rock hounds abound
But you don’t have to be an amateur geologist to understand the impressive geologic variety found along the Oregon coast. All you need is a healthy sense of adventure to go rock hunting for an array of treasures that may wash ashore, or be hidden behind some driftwood. From agates to ocean-eroded sea glass, from obsidian to jaspers and petrified wood, the coastline is a trove of geologic residue.
Fans of rock hunting also should not hesitate to visit the one-of-a-kind Yachats rock shop, Styx, Stones n’ Bones, 160 W 2nd St. Owners Marc and Jen Taylor have amassed quite the collection of rocks, fossils, even complete skeletons, by combing estate and collection sales.
Marc, a Yachats native, admires the beauty and mystery of the natural world. With more than 1,900 pieces in the shop, this beauty and mystery is on full display.