Four Craters Lava Field

Infobox Mountain
Name = Four Craters Lava Field
Photo = FourCraters LeeSiebert 088048.jpg
Caption = Craters of the aptly named Four Craters Lava Field are seen here from the NW on Green Mountain.
Elevation= convert|4924|ft|mVNUM|1=1202-14- accessdate|2008-05-12]
Location = Oregon, USA
Range =
Prominence =
Coordinates = coord|43.361|-120.669|display=inline,title
Topographic

Type = volcanic field
Volcanic_Arc/Belt =
Age = Holocene?
Last eruption = < 50,000 years agocite web | title = Oregon Volcanoes - Four Craters Flows | work = Deschutes & Ochoco National Forests - Crooked River National Grassland | publisher = United States Forest Service | date = 2003-12-24 | url = http://www.fs.fed.us/r6/centraloregon/geology/info/volcanoes/fourcraters.shtml | accessdate = 2008-05-12]
First ascent =
Easiest route =

Portions of this article include public domain text from the USFS [http://www.fs.fed.us/r6/centraloregon/geology/info/volcanoes/fourcraters.shtml Deschutes & Ochoco National Forests - Crooked River National Grassland] .

Four Craters Lava Field is a basaltic volcanic field located south east of Newberry Caldera in the U.S. state of Oregon. The volcanic field covers about 30 square kilometers. Four Pleistocene cinder cones are the source of the flows in the field and are aligned along a fissure trending N 30° W. The cones rise 75 to 120 meters above the flows and the distance between the northern most and southern most cones is about 3.5 kilometers.

Closely related to the Four Craters lava field is Crack-in-the-Ground located at the southwest corner of the field. The eruptions from the field were accompanied by a slight sinking of the older rock surface. This shallow, graben-like sink is about 3 kilometers wide and extends to the south into an old lake basin. Crack-in-the-Ground marks the western edge of this small, volcano-tectonic depression and is nearly 9 meters deep and over a meter wide. The crack is the result of a tension fracture along a hingeline produced by the drapping of Green Mountain lava flows over the edge of upthrown side of the concealed fault zone.

References

Further reading

*cite journal
last = Peterson
first = Norman V.
coauthors = Edward A. Groh
title = CRACK-IN-THE-GROUND, LAKE COUNTY, OREGON
journal = The Ore Bin
volume = 26
issue = 9
pages = pp. 158-166
publisher = State Of Oregon - Department of Geology and Mineral Industries
location = Portland, Oregon
date = September 1964
url = http://ir.library.oregonstate.edu/dspace/bitstream/1957/2741/1/vol26_no9_ocr.pdf
format = PDF
accessdate = 2008-08-21
*cite journal
last = Peterson
first = Norman V.
coauthors = Edward A. Groh
title = RECENT VOLCANIC LANDFORMS IN CENTRAL OREGON
journal = The Ore Bin
volume = 25
issue = 3
pages = pp. 33-45
publisher = State Of Oregon - Department of Geology and Mineral Industries
location = Portland, Oregon
date = March 1963
url = http://ir.library.oregonstate.edu/dspace/bitstream/1957/2638/1/vol25_no3_ocr.pdf
format = PDF
accessdate = 2008-08-21