Water, geology, climate & soils: , Merced River & Central Valley connections

Geography & geology Merced River basin

Climate & hydrology Roger Bales Soils & soil formation UC Merced Water, in all its forms, is indeed the crowning glory of the Sierra. Whether in motion or at rest, the waters of the Sierra are a constant joy to the beholder. Above all, they are the Sierra’s greatest contribution to human welfare. F. Farquhar, 1965. History of the Sierra Nevada

Bierstadt, 1863-75 Contemplating the lace-like fabric of streams outspread over the mountains, we are reminded that everything is flowing somewhere, animals and so called lifeless rocks as well as water.. . J. Muir, 1911, My First Summer in the Sierra

Bierstadt, 1863-75 The Sierra Nevada & Central Valley

Sacramento

San Francisco

Fresno

N

050100 miles The long past of the Sierra Nevada 135 million 4,500 million 20,000 65 million 38 million 570 million 400,000 225 million 3 million present 1 million

ancient seas days of fire & volcanoes forms gold days of ice deposits erosive times mountains tremble, lift & tilt Mammoth Melting of last ice age

M. Hill, Geology of the Sierra Nevada, 1975 Mountain erupts & the days of ice

before after

M. Hill, Geology of the Sierra Nevada, 1975 Yosemite Valley today

Douglas Alden UCSD-SIO 2005 “The Range of Light” & “Snowy Range”

Obata, Audette, above the Merced River

Where has all of this rock gone?

Douglas Alden UCSD-SIO 2005 Geology of the Sierra Nevada Diverse geological activities have produced a broad suite of rock formations in the Sierra Nevada, dominated by granite but including many types of igneous, sedimentary & metamorphic rocks. Geology of the Sierra Nevada

Because the Sierra Nevada is underlain by mostly granitic rocks, soils are thin & rocky. Although the fertility of the soil in general over the Sierra Nevada is rather low, the range contains some of the most productive sites for conifers in the world. Many individual rivers drain the western slopes of the Sierra Nevada, flowing eventually into Topography of Upper Merced river basin

Yosemite Valley Merced river headwaters are covered with snow in winter & spring Satellite snowcover Much of the precipitation falls as snow at high elevations % SCA 76-100 51-75 26-50 Tuolumne 1-25

Merced

May 10, 2004 Streamflow peaks during spring snowmelt Peaks occur in late spring to early summer Headwaters receive little summer precipitation & are largely snow free by late summer Streams flow year round Merced river profile

Triple Divide 10000

8000

6000 Yosemite Valley 4000 Elevation, ft Merced river canyon Snelling 2000

100 80 60 40 20 0 miles Streams enter the U-shaped Yosemite Valley from higher V-shaped canyons From Yosemite Valley the river drops to El Portal & the Merced River Canyon Merced river canyon near Briceburg Soil formation is a result of 5 factors – Physical & chemical composition of the parent material –Climate – Relief, or lay of the land – Biological forces – Length of time the forces have been in operation Soil formation along Merced river

– River & glacial erosion brought material down from the mountains to form the agricultural soils in the & along the Merced river – Glacial outwash is the main source of parent material for the soils in the terraces & fans of the Merced river; exception is that some Holocene alluvium is derived from metamorphic terrane of foothills (including granitic debris) Sediment is transported during large floods Soil profiles along river terraces

Terrace & fan deposits along the Merced river range from 200 years to 3 million years in age from Pavich et al., 1986 Older soils, Sierra foothills near Snelling Younger soils along Merced river near Snelling

Daily temperature

Vineyard 1 Daily temperature

Vineyard 2 Temperature comparison Daily temperature Daily temperature Questions?