麟 Tips and Safety
- Pull off carefully and use hazard lights—this is a roadside location.
- No climbing, digging, or collecting is necessary—observe respectfully.
- Be aware of passing traffic and stay alert while exploring.
Logging Requirements
To claim this EarthCache 
, you must first visit the posted coordinates and then Send Answers via the geocaching.com Message Center to the following questions based on your observations and the information provided in the short Earthcache Lesson below:
易 Question 1: Estimate the angle of tilt in the visible rock layers. Are they vertical, steep, or gently sloped?
易 Question 2: Can you spot any areas where the rocks seem to be cracked or broken? If so, what natural forces might have caused these fractures?
Bonus (Optional): Snap a photo of you or your mascot doing a “tectonic twist” pose.
Earthcache Lesson: This quiet roadside stop to the beach may seem ordinary—but it hides an epic geologic tale! Right here at Analyde Gap Road, you're standing on ancient ocean crust, built by lava eruptions near a hotspot similar to today’s Hawaiian Islands. Over millions of years, this crust traveled across the ocean, slammed into North America, was lifted skyward by tectonic collisions, then scraped by giant Ice Age glaciers.
Pretty wild for a road cut, right?
This EarthCache invites you to explore the rocks along side this beach access —and to imagine how underwater volcanoes and a migrating crust all left their mark on this very spot.
A Hawaiian Connection
Let’s rewind about 50 million years, when a massive volcanic plateau began forming deep underwater in the Pacific Ocean. These eruptions likely came from a mantle hotspot—a plume of molten rock rising through the Earth’s mantle. Sound familiar? That’s because something similar is happening right now in the middle of the Pacific Ocean: the Hawaiian Islands!
Just like the Hawaiian chain, this ancient volcanic activity produced layer upon layer of basalt lava, which hardened into what we now call the Siletzia terrane. But unlike Hawaii—which remains isolated in the ocean—Siletzia was slowly moving east, riding atop the Farallon Plate.
Eventually, it collided with North America. And that’s when the fun really began.
隣 Collision Course: Terrane Meets Continent
When the volcanic mass of Siletzia slammed into the edge of the continent, it didn’t just bounce off. It fused to North America, a process geologists call accretion. This is how much of western North America formed—by sticking on chunks of land from elsewhere!
The collision crumpled and shoved the once-horizontal lava flows, forcing them upward and twisting them into steep angles. Analyde Gap road is at the trailing of the Siletzia and the Olympic mountain range further inland (and nearly 8,000 ft above sea level) is the leading edge. Between the two is the seemingly chaotic ups and downs and bends of the road on your way to this spot (a fun or scary drive depending on the weather) where the Siletzia collided and accordioned to fuse against North America.
Albeit most are covered in sand and shrubbery, the exposed rocks you are seeing at Analyde Gap road are remnants of the Crescent Formation, which is Siletzia’s volcanic "skin”.
❄️ The Icy Overprint
To add to the geological excitement, much later, during the Pleistocene Ice Ages, this region felt the chilling influence of continental glaciers. While the thickest ice remained further north, the Olympic foothills were not spared. Glaciers pushed through valleys, scraped slopes, and left behind a mix of rounded rocks and fine sediments.
At Analyde Gap Road, you might notice mixed in:
- Rounded glacial erratics — rocks carried by ice from distant locations.
- Unsorted gravel and sediment — dumped when glaciers melted.
- Smoothed or grooved rock faces — signs of glacial abrasion.
These features overlay the older volcanic rocks and add another layer to the story—literally.
⛰️ Tectonic Uplift: It’s Still Happening
Today, the story isn’t over. The Cascadia Subduction Zone, located offshore, continues to drive tectonic activity. The Juan de Fuca Plate is sliding beneath the North American Plate, forcing the land to rise—slowly but surely.
This uplift is raising the Olympic Mountains and nearby terrain (like this roadcut!), and shaping rivers, valleys, and hills. That’s why you might see steep slopes, landslides, and sharp ridgelines—evidence of a landscape still in motion.
吝 What to Look for at the Site
At Analyde Gap Road, pull over safely and take a close look at the exposed rocks at this roadcut:
- Examine the dark basalt rock—these are ancient lava flows!
- Look around for glacial clues—rounded rocks, mixed sediments, or smoothed surfaces.
The Beach view stands out, of course, but look closer and you’re seeing three major geologic forces at play:
Volcanoes (like Hawaii!)
Tectonics (continental collision and uplift)
❄️ Glaciation (Ice Age overprinting)
++++++Sources:
https://pubs.usgs.gov/publication/70117448
https://www.washingtonminerals.com/cres.html
https://www.nps.gov/parkhistory/online_books/olym/schalk/chap5.htm
https://people.earth.yale.edu/sites/default/files/files/Long/gao_long_2022_elements.pdf