GRAY BUTTE

This travel bug was activated on Easter 2010. Please travel along to help it discover new places and friends.

The spectacular landscape of today’s Oregon was shaped over millions of years by fire and flood, earthquakes and eruptions, and the movement of oceans and continents on a huge scale.

Imagine some of the largest lava flows in the history of the world blanketing the state. Imagine thousands upon thousands of volcanic eruptions, and ancient floods that carried enough water to equal the combined flow of all the rivers in the world. This is the Oregon that geologists see. And the geology that we Central Oregonians see includes snow-capped mountains, cinder cones and buttes.

Oregon is the most volcanic state in the continental United States. Volcanoes are responsible for the formation of most of the rocks formed in Oregon over the past 45 million years. The rocks and landscapes that one sees while driving between The Dalles and Sunriver are nearly all related, in one fashion or another, to volcanism.

The earliest volcanism recorded in Central Oregon occurred during the geologic epochs of the Eocene and Oligocene. Volcanic rocks of this age are most common in the Ochoco Mountains, located to the east of U.S. Highway 97. Eruptions from small rhyolite volcanoes in central Oregon also produced widespread ash-flow tuffs. Rhyolite lavas formed steep domes south of Madras. The youngest known eruption in central Oregon produced the Big Obsidian Flow in Newberry Crater 1300 years ago. There are no signs that volcanism will let up in the future. The most recent episode of volcanism produced the High Cascades and the high volcanic peaks perched on the crest such as the Three Sisters, Broken Top, and Mt. Jefferson. Elsewhere in the Cascades the chemistry of the lavas and short length of lava flows created much steeper and taller cones such as BLACK BUTTE (elevation 6,436) and Odell Butte. In 1980, Mount St. Helens in neighboring Washington erupted violently, temporarily reducing the Columbia River's depth to as little as 13 feet, and disrupting Portland's economy. The eruption deposited ash as far into Oregon as Bend.


GRAY BUTTE (elevation 5,092 ft.) is composed of basalt flows and sediment containing leaf fossils and topped by a thick rhyolitic lava flow cap. The leaf fossils document a change from sub-tropical to temperate climate in Central Oregon between 30 and 40 million years ago.

Highway 97 crosses a saddle between JUNIPER BUTTE (elevation 3,925 ft.) on the west and Haystack Butte on the east. These buttes mark the western edge of the Ochoco Mountains, a part of the Blue Mountains, which extend 200 miles northeastward into southeast Washington. Juniper Butte is a rhyolite dome, as is CLINE BUTTE (elevation 4,117), visible about 15 miles to the south.

POWELL BUTTE (elevation 5,235), located in Crook County is an old rhyolitic highland of Clarno (Eocene) age. It is a dominant feature in the Central Oregon landscape.

These are just a few of the buttes in the Oregon landscape but certainly some with which many geocachers are quite familiar.