Lake Modoc is a former lake in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

and

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

, in the location of present-day

Upper Klamath Lake Upper Klamath Lake (sometimes called Klamath Lake) ( Klamath: ?ews, "lake" ) is a large, shallow freshwater lake east of the Cascade Range in south-central Oregon in the United States. The largest body of fresh water by surface area in Oregon, it ...

Lower Klamath Lake Lower Klamath Lake is a lake in Siskiyou County, California. At one time it was connected to Upper Klamath Lake. It currently is used to hold overflow water for Klamath Project irrigation uses. The lake is in Northern California, near the borde ...

and

Tule Lake Tule Lake ( ) is an intermittent lake covering an area of , long and across, in northeastern Siskiyou County and northwestern Modoc County in California, along the border with Oregon. Geography Tule Lake is fed by the Lost River. The eleva ...

. It existed during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

epochs, its formation probably influenced by volcanism and faulting. The bed of the former lake had plentiful resources for early humans, and today it is used for agriculture.

Background

It has been known for over a century that large lakes previously existed in the

Western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the We ...

, most notably

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

Lake Lahontan Lake Lahontan was a large endorheic Pleistocene lake of modern northwestern Nevada that extended into northeastern California and southern Oregon. The area of the former lake is a large portion of the Great Basin that borders the Sacramento Rive ...

and

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

Lake Bonneville Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperature ...

. Such lakes also formed in

eastern Oregon Eastern Oregon is the eastern part of the U.S. state of Oregon. It is not an officially recognized geographic entity; thus, the boundaries of the region vary according to context. It is sometimes understood to include only the eight easternmost ...

, where present-day

Malheur Lake Malheur Lake is one of the lakes in the Malheur National Wildlife Refuge in Harney County in the U.S. state of Oregon. Located about southeast of Burns, the lake is marsh fed by the Donner und Blitzen River from the south and the Silvies Rive ...

and Goose Lake are remnants of former pluvial lakes. Lake Modoc was so named by Samuel N. Dicken, professor of geography at the

University of Oregon The University of Oregon (UO, U of O or Oregon) is a public research university in Eugene, Oregon. Founded in 1876, the institution is well known for its strong ties to the sports apparel and marketing firm Nike, Inc, and its co-founder, billion ...

. The region of Lake Modoc was first described during the early and mid-19th century.

The lake

Lake Modoc was a pluvial lake that existed during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

in basins formed by faulting and volcanism. It covered a length of from south of Tule Lake in California to near present-day

Fort Klamath Fort Klamath was a military outpost near the western end of the Oregon Trail, between Crater Lake National Park and Upper Klamath Lake in Klamath County, Oregon, United States. The Fort Klamath Site, about a mile southeast of the present communi ...

in Oregon, its waters reaching an elevation of about above sea level and covering an area of about with a highly irregular shape. Several islands formed in the lake, such as the Klamath Hills, present-day Miller Hill close to

Klamath Falls Klamath Falls ( ) is a city in and the county seat of Klamath County, Oregon, United States. The city was originally called ''Linkville'' when George Nurse founded the town in 1867. It was named after the Link River, on whose falls the city was ...

and Turkey Hill close to Malin. The shoreline of Lake Modoc is well visible close to

Hydrology

Unlike other pluvial lakes, Lake Modoc had a steady inflow of surface water, owing to its proximity to snow- and glacier-covered mountains of the Cascade Range. Its watershed extended over present-day Modoc and Siskiyou counties (both in California), and

Jackson Jackson may refer to: People and fictional characters * Jackson (name), including a list of people and fictional characters with the surname or given name Places Australia * Jackson, Queensland, a town in the Maranoa Region * Jackson North, Qu ...

Klamath Klamath may refer to: Ethnic groups *Klamath people, a Native American people of California and Oregon **Klamath Tribes, a federally recognized group of tribes in Oregon *Klamath language, spoken by the Klamath people Places in the United States * ...

and

Lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

counties (all in Oregon), including the Williamson River, Sprague River and Lost River. Cinder,

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v ...

and

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

from the Cascades filled the lake. Lake Modoc also featured an outflow, at first to the south before a lava flow blocked it, although seepage continued from there to this day. Presently, the

Klamath River The Klamath River (Karuk: ''Ishkêesh'', Klamath: ''Koke'', Yurok: ''Hehlkeek 'We-Roy'') flows through Oregon and northern California in the United States, emptying into the Pacific Ocean. By average discharge, the Klamath is the second large ...

drains the area. Given that the basin at present cannot hold a lake the size of Lake Modoc, it is likely that its formation and demise was influenced by the existence of outlets.

History

Lake Modoc was probably formed by geologic processes such as faulting or by the

Medicine Lake Volcano Medicine Lake Volcano is a large shield volcano in northeastern California about northeast of Mount Shasta. The volcano is located in a zone of east-west crustal extension east of the main axis of the Cascade Volcanic Arc and the Cascade R ...

blocking a former southward-draining outlet. The lake appears to have existed during the Pleistocene and late Pliocene, with some lake deposits estimated to be at least 3 million years old. During marine oxygen isotope stage 4, Lake Modoc was deep and cold. Water levels began to decrease as the Pleistocene ended, as the climate became drier and the outlet to the Klamath River lower. The former lake floor is nearly level, and the shoreline is almost unwarped. Today,

and

remain from Lake Modoc; Upper Klamath Lake is the largest present-day lake in Oregon by surface area. The floor of the drying lake featured deep soils and abundant vegetation, water and wildlife; thus it was quickly populated by humans who migrated there over 3,000 years ago. The former lake bed is now used as

cropland Agricultural land is typically land ''devoted to'' agriculture, the systematic and controlled use of other forms of lifeparticularly the rearing of livestock and production of cropsto produce food for humans. It is generally synonymous with bot ...

, and agriculture is the most prevalent human land use in the region. Part of the southern shoreline has been covered by lava flows, and geologic processes have continued into the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

; the Glass Mountain lava flow was emplaced about 1,000 years ago, and some Holocene lava flows have been faulted.

References

Works cited

* * {{DEFAULTSORT:Modoc, Lake Pleistocene North America Pliocene North America Pliocene California Klamath River Lakes of California Lakes of Oregon Geology of Oregon Lakes of Modoc County, California Lakes of Siskiyou County, California Lakes of Jackson County, Oregon Lakes of Lake County, Oregon Lakes of Klamath County, Oregon Former lakes of the United States