Saddle Mountain, the highest peak in Clatsop County in Oregon’s northwestern Coast Range, was created about 15 million years ago when lava in the ancient Columbia River valley met the Astoria Sea, producing steam explosions and volcanic breccia made of fused basalt fragments. Its striking form made it a notable landmark for explorers, including British captain John Meares in 1788, Lewis and Clark in 1805, and the Wilkes Expedition in 1841. Now it is best known as a hiking destination, with a demanding trail to its higher summit and broad views stretching from the Pacific Ocean to prominent Cascade volcanoes.