| Round Top | |
|---|---|
 View to the west from the summit of Round Top.Carleton Watkins, 1879. | |
| Highest point | |
| Elevation | 10,381 feet (3,164 m)[1] |
| Prominence | 2,541 feet (774 m)[1] |
| Parent peak | Highland Peak[2] |
| Isolation | 13.66 miles (21.98 km) to Freel Peak[1] |
| Listing | Sierra Peaks Section |
| Geography | |
 | |
| Parent range | Sierra Nevada |
| Geology | |
| Mountain type | Volcano |
| Volcanic arc | Sierra Nevada |
| Last eruption | 5 million years ago |
Round Top is a 10,381-foot (3,164 m) mountain located on theSierra crest inAlpine County, California, United States.[3] Its summit is the highest point inEldorado National Forest and theMokelumne Wilderness.[1] The mountain lies just south ofCarson Pass. With 2,541 feet (774 m) ofprominence, Round Top is the 16th most prominent mountain in theSierra Nevada.[4]
Round Top is the remnant of avolcano that formed in theMiocene epoch, which lasted fromc. 23 million years ago toc. 5 million years ago. Most of the mountain's vertical height consists of anintrusive[5]volcanic plug[6]: 3 formed ofbasaltic andesite.[5] This intrusive structure formed under the volcano's surface as subsurfacemagma gradually cooled and solidified. Approximately 3,000 feet (910 m) is exposed by the northern wall of Summit City canyon, which forms the south face of the mountain. A strong magnetic anomaly in the vicinity indicates that this plug further extends far below the canyon floor.[6]: 5 The upper layers of the mountain are made up ofextrusive rocks, which formed at the surface.[6]: 5 A succession of lava flows form the bulk of these upper layers. Some solidified mudflows are also present.[6]: 5 The rock that forms Round Top was more resistant toerosion than other strata of thevolcano. Eventually, over ageologic time scale, these other strata wore away, revealing the erosion-resistant remnants which make up the mountain that remains today. It has a flanklava dome, calledElephants Back.
The north slope of Round Top is home to a number of tree species, most prominentlywhitebark pine,western white pine, andlodgepole pine. The summit of the mountain rises above thetree line. Western white pine and lodgepole pine grow up to about 8,960 feet (2,730 m). The whitebark pine survives in the form of short, stubbykrummholz to as high as 9,650 feet (2,940 m).[7] A specimen of theLake Tahoe lupine (Lupinus meionanthus) has been identified at the summit of Round Top.[8]
In 1872, prospectors began exploring the Summit City Creek canyon immediately south of Round Top, ultimately filing more than 30 mining claims in the area.[6]: 4 At some point before 1879, George Davidson of theUnited States Coast and Geodetic Survey established ageodetic station on the summit of the mountain, as part of a chain of such stations atop peaks along the Sierra crest.[9]
Round Top is listed on theSierra Peaks Section peak list. Reaching the summit requires aYDS class 3 ascent.[10] The circumstances of the first ascent are unknown.
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38°39′49″N120°00′05″W / 38.66352°N 120.00129°W /38.66352; -120.00129
