Twin Rocks

After millions of years, the two sea stacks of Twin Rocks connected to form a single structure. Prior to 1925, Twin Rocks was called Profile Rocks until it was changed to avoid a name conflict with another geologic formation in the region. If you look closely, you can see a sea dragon, Indian princess or Loch Ness monster. The rock is 88 feet at its pinnacle and the hole is 35 feet across; you could actually fly a helicopter between the two formations. When viewed from above, the rocks are seen as a narrow, wedge shape perched on top of a rocky island.

Did you ever wonder how the Twin Rocks formation (and others like it along the Oregon coast) was created? According to George R. Priest, a geologist with the Oregon Department of Geology and Mineral Industries’ coastal field office in Newport, Twin Rocks is composed of sandstone formed between 20 million and 30 million years ago. At that time, the entire area, including what is now the Coast Range, was an undersea marine environment and part of the continental shelf, just as the ocean floor off the coast is today.

Over time and under pressure, the sand in the seabed consolidated into sandstone. Then, as the Earth’s tectonic plates crashed into one another, they pushed up the coastal mountains, fractured and tilted up a ridge of sandstone along the coastline. Over time, the tides and surf wore away the softer portions of the sandstone, leaving behind the massive rocks we see today.

If you’d like to know more about the geologic history of the Oregon Coast, Priest recommends the book Geology of Oregon by Elizabeth and William Orr, which can be found in most libraries around the state.