Howlock Mountain is a heavily eroded shield volcano

Shield volcano

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...

 in the Cascade Range

Cascade Range

The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 of central Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, located along the Cascade Crest just north of Mount Thielsen

Mount Thielsen

Mount Thielsen, or Big Cowhorn, is an extinct shield volcano in the Oregon High Cascades, near Mount Bailey. Because Mount Thielsen stopped erupting 250,000 years ago, glaciers have heavily eroded the volcano's structure, creating precipitous slopes and its horn-like peak...

. Ice Age

Ice age

An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

 glaciers eroded away most of the flanks of the volcano, leaving numerous deep cirques

Cirque (landform)

thumb|250 px|Two cirques with semi-permanent snowpatches in [[Abisko National Park]], [[Sweden]].A cirque or corrie is an amphitheatre-like valley head, formed at the head of a valley glacier by erosion...

 surrounding a central ridge capped by several horns. The summit of Howlock Mountain is located on the Cascade Crest, which lies along the border between Douglas County

Douglas County, Oregon

-National protected areas:* Crater Lake National Park * Rogue River-Siskiyou National Forest * Siuslaw National Forest * Umpqua National Forest * Willamette National Forest -Adjacent counties:* Lane County, Oregon -...

 and Klamath County

Klamath County, Oregon

-National protected areas:* Bear Valley National Wildlife Refuge* Crater Lake National Park * Deschutes National Forest * Fremont National Forest * Klamath Marsh National Wildlife Refuge* Lower Klamath National Wildlife Refuge...