As this air is forced over the mountains, it cools and releases moisture in the form of rain or snow. At lower elevations rain nurtures the forests while at higher elevations snow adds to glacial masses that relentlessly carve the landscape. The mountains wring precipitation out of the air so effectively that areas on the northeast corner of the peninsula experience a rain shadow and get very little rain. The town of Sequim gets only 17 inches a year, while less than 30 miles away Mount Olympus receives some 200 inches falling mostly as snow. A number of new theories have been presented recently regarding the origin of the Olympics.
Geologists continue to discover new information that contributes to the debate.
The following theory is the one that has been accepted for a number of decades. These mountains have arisen from the sea. For eons, wind and rain have washed sediments from the land into the ocean. Over time these sediments were compressed into shale and sandstone. Meanwhile, vents and fissures opened under the water and lava flowed forth, creating huge underwater mountains and ranges called seamounts.