Geology
Humbug Mountain was created about 130 million years ago, in the early Cretaceous period. It was formed when islands in the Klamath microcontinent collided, uplifting primordial mountains composed of mostly sandstone. Ancient rivers eroded these mountains, and the sediment and sandstone was deposited on the seashore. Then, the microcontinent collided with the North American continent, uplifting Humbug Mountain in the process. Near the summit, rock outcrops of granite and sandstone can still be found.
The mountain now stands 1,756 feet (535 m) above sea level, and is one of the highest mountains in Oregon to rise directly from the ocean. It is considered a headland.
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