# Mount Thielsen

- **Country:** United States
- **Coordinates:** 43.152837, -122.066514
- **Age:** About 290,000 years
- **Topo:** USGS Mount Thielsen
- **Type:** Shield volcano
- **Range:** Cascades
- **Listing:** Oregon county high points
- **Location:** {{unbulleted list
- **Formed By:** Subduction zone volcanism
- **Elevation Ft:** 9184
- **First Ascent:** by E.E. Hayden
- **Volcanic Arc:** Cascade Volcanic Arc
- **Easiest Route:** Scramble
- **Prominence Ft:** 3342

Mount Thielsen (Klamath: hisc’akwaleeʔas), is an extinct shield volcano in the Oregon High Cascades, near Mount Bailey. Because eruptive activity ceased 250,000 years ago, glaciers have heavily eroded the volcano's structure, creating precipitous slopes and a horn-like peak. The spire-like shape of Thielsen attracts lightning strikes and creates fulgurite, an unusual mineral. The prominent horn forms a centerpiece for the Mount Thielsen Wilderness, a reserve for recreational activities such as skiing and hiking. Thielsen is one of Oregon's Matterhorns.

![Photo of Mount Thielsen](https://upload.wikimedia.org/wikipedia/commons/1/11/Mt._Thielsen.jpg)

**Source:** https://en.wikipedia.org/wiki/Mount_Thielsen (Wikipedia, CC BY-SA)