Soils Field Trip to North & East

Day 1: SF to Hendy Woods State Park

We'll start our look at the Golden Gate Bridge.

On the south side of the Waldo tunnel fog drip reduces the tendency for the more seasonally extreme xeric moisture regime, and the ustic regime predominates: argiustolls are common on the hillsides. In Marin County, hillside soils north of the tunnel are typically xerolls and xerepts. In valley floors from the Hwy 37 turnoff near Novato to near Cotati are abundant Reyes Fluvaquents and Clear Lake clay Endoaquerts, associated with deposition of fine sediments in this broad structural valley that drains to the San Francisco Bay.

Xeric vs. Ustic moisture regimes

To be xeric, the entire moisture control section of a soil profile must be dry in the summer for 45 consecutive days in 6 out of 10 years.  The ustic moisture regime includes summer-dry climates, but not those that do not meet this requirement.  Fog is the likely reason why the more coastal soils don't experience this.

Order Mollisols "oll"
  • mollic epipedon
  • dark color (< 3.5 moist, < 5.5 dry)
  • base saturation > 50%
  • not too hard, not too dry

Suborder Ustolls ustolls.jpg (6733 bytes)xerolls.jpg (42687 bytes)

  • ustic soil moisture regime
  • US Great Plains wheat belt and Dust Bowl,
    developed on prairie grasses

Great Group Argiustolls

  • argillic horizon

Suborder Xerolls

  • driest of the mollisols
  • widespread in Idaho, Utah, Washington, and Oregon
  • central Turkey

 


 
Series properties geographic setting distribution & extent
Reyes
Fine, mixed, acid, thermic Sulfic Fluvaquents
deep, somewhat poorly drained soils that formed in alluvium from mixed sources. Reyes soils are in reclaimed and protected marsh areas and have slopes of 0 to 2 percent Mainly around the edges of Suisun and San Pablo Bays and scattered in the Sacramento Delta in California. The series is of moderate extent.
Clear Lake
Fine, smectitic, thermic Xeric Endoaquerts
very deep, poorly drained soils that formed in fine textured alluvium derived from sandstone and shale basins and in swales of level drainageways In small valleys of the Coast Range and along the San Joaquin and Sacramento Valleys. The soils are moderately extensive

Past Santa Rosa, the highway crosses to the Russian River drainage. River deposits and adjacent terraces are dominated by the Yolo-Cortina-Pleasanton Association we'd see along Hwy 101 well into Mendocino County: Cortina Xerofluvents near and occasionally in the channel, Yolo Xerorthents on the flood plain (we'll discuss these later, when we get to the Central Valley), and Pleasanton Haploxeralfs on older terraces. Xerepts occur on forested steeper slopes higher up. North of Healdsburg we briefly pass through the Spreckels-Felta Association of palexeralfs and argixerolls developed on old lahar deposits.

xeralfs.jpg (50652 bytes)xeralfs80.jpg (41645 bytes)

 

 

 

 

 

 

 

 

Order Alfisols "alf"

  • typical forest soils; in eastern US, found just E (wet side) of mollisols
  • from "pedalfers" -- aluminum and iron 
  • argillic horizon
  • BS > 35%, but probably < 50%

Suborder Xeralfs

  • xeric moisture regime
  • one of the most common suborders in California, often associate with oak woodland sites

Great Group Haploxeralfs

  • Haplo- for minimum horizons -- grab-bag for simple xeralfs

Great Group Palexeralfs

  • pale - "old" (as in paleontology) -- from well-developed argillic horizon
Order Entisols "ent"
  • young -- doesn't meet any other qualifications for other orders, for
    various reasons.

Suborder Aquents aquents57.jpg (7504 bytes)

  • aquic moisture regime
  • wetlands -- bay muds
  • Florida Everglades, SF Bay margins

Great Group Fluvaquents

  • fluv- alluvial flood plain soils

Suborder Fluvents

  • recent flood plain deposits
  • (without an aquic moisture regime)

Suborder Orthents

  • orth- = "true" -- meaning nothing special
  • usually shallow to bedrock, often on steep eroded slopes
  • also a "catch-all" -- Yolo not a fluvent
  • some cut-and-fill urbanized soils
  • Labrador (glacially eroded) , mountainous areas of N. Australia, Rockies, Sierra
Series properties geographic setting distribution & extent
Yolo
Typic Xerorthents
thick grayish brown, neutral silt loam A horizons and brown and pale brown mildly alkaline silt loam C horizons. nearly level to moderately sloping alluvial fans. The soils formed in fine-loamy alluvium derived from sedimentary formations West site of Sacramento Valley, central California, and in the valleys of the California Coast Range. The series is extensive.
Cortina
Typic Xerofluvents
formed in gravelly alluvium from from mixed rock sources nearly level to strongly sloping and are in small valleys and on alluvial fans and floodplains at elevations of 25 to 2,400 feet. They formed in recent gravelly and cobbly alluvium derived from old terrace deposits and a variety of resistant metamorphic and sedimentary rock sources Sacramento Valley and smaller valleys in the Coast Range in norhtern, central and southern California; moderately extensive
Pleasanton
Mollic Haploxeralfs
grayish brown, slightly acid or neutral, gravelly fine sandy loam A horizons; brown, neutral, gravelly sandy clay loam B2t horizons; and gravelly fine sandy loam C horizons nearly level to gently sloping alluvial fans and terraces at elevations of less than 2,400 feet valleys of the Coast Range, Central Valley, and intermountain valleys of southern California. They are moderately extensive.
Series properties geographic setting distribution & extent
Spreckels
Fine, mixed, mesic Ultic Palexeralfs
grayish brown and light brownish gray slightly acid, loamy A horizons; brown, strongly acid clay B2t horizons; and brown very gravelly clay C horizons on sloping to hilly uplands of tuffaceous sediments Sonoma County, and Shasta County, California and possibly in other nearby counties. The soils are inextensive
Felta Loamy-skeletal, mixed, thermic Pachic Argixerolls grayish brown, slightly acid, very gravelly heavy loam A horizons and grayish brown, slightly acid, very gravelly clay loam B2t horizons underlain by gravelly old alluvium on dissected terraces; formed in mixed gravelly alluvium from mixed igneous rocks Sonoma and Napa Counties, California. The soils are moderately extensive

Just past Cloverdale, turn left on Hwy 128 for Mendocino and Fort Bragg. The highway gradually crosses a divide to the Navarro River which we'll follow to the coast. As we climb to the divide, residual soils developed in Franciscan assemblage rocks produce many detailed changes. The general tendency is for a gradual shift from haploxeralfs associated with oak woodlands on the lower hillsides, to the more eroded xerepts and ultisols developed in association with forested soils of higher rainfall and greater erosion rates, on upland sites. Significant exceptions occur on serpentinite outcrops where xerolls are favored. Floodplains of the Navarro River are dominated by fluvents and riverwash.

inceptisols.jpg (42103 bytes)Order Inceptisols "ept"
  • young, but has cambic subhorizon
    or an umbric (not quite mollic) epipedon
  • suborders based mainly on moisture regime:  
    • aquepts
    • ustepts
    • udepts
    • xerepts
    • cryepts (cryic temperature regime)
    • anthrepts (plaggen or anthropic horizon)
Series properties geographic setting distribution & extent
Woodin
Loamy-skeletal, mixed, mesic Typic Dystroxerepts
gravelly (to extremely gravelly) sandy loam; lithic contact; 20-95% gravel on hills and mountains. Slopes are 9 to 75 percent. Elevations are 500 to 4,250 feet Northern coastal California. The series is not extensive.

Camp: Hendy Woods State Park

We'll set up camp and then go exploring soils, trying to find a good soil transect. We'll use the soil auger to observe a series of soil profiles from the base of the slope to the nearest rise. Then explore along the river to look at soil development there.

Soils of Hendy Woods State Park
Gschwend and Frenchman
Ustic Dystrustepts
very deep, well drained soils formed in alluvium In campground, on river terraces; they are 20 to 200 feet above present river levels and do not flood. Slopes are 0 to 9 percent. Elevations are 250 to 1,700 feet; Doug-fir, tanoak, etc. Northern coastal California. not extensive.
Ornbaun - Zeni Ultic Haplustalfs
Ornbaun: Fine-loamy, mixed, isomesic Ultic Haplustalfs
deep; developed on sandstone; reddish yellow subsoil At higher elevations, in mountains, above terraces; 200 to 2,500 feet Northern coastal California. The series is moderately extensive
On the floodplain: Feliz and Talmage Haploxerolls 140 Feliz Cumulic Haploxerolls (10YR 4/2) clay loam and 210 Talmage Fluventic Haploxerolls gravelly sandy loamon floodplains

Fill in the depth (in cm), Munsell Color, and Consistency of each of the following locations and horizons:

horizon

property

Base of Slope

Midway Upslope

Crest of Slope

A

depth, color:

           
 

consistency:

     

B?

depth, color:

           
 

consistency:

     

C?

depth, color:

           
 

consistency:

     

Day 2: Pygmy Forest and Hwy 20 transect

Morning: At the coast, take Hwy 1 north to Jug Hangle State Reserve. Along the coast are forested areas of tropohumults and albaquults and various mollisols developed on younger grass-developed terraces and tropofluvents (like Bigriver series) on river floodplains.

series properties geographic setting distribution & extent
Bigriver
Coarse-loamy, mixed, nonacid, isomesic Typic Tropofluvents
very deep, well drained soils formed from alluvium; buried soils, etc.
Irregular organic carbon distribution (typical of fluvents)
flood plains. Slopes are 0 to 5 percent. Elevations are 0 to 125 feet Northern coastal California and southwestern Oregon. The series is not extensive
ultisols.jpg (32820 bytes)Order Ultisols "ult"
  • low base saturation <35%
  • argillic horizon

Suborder Humults and other Ultisols suborders

  • Humults high in OM, due to litter input
  • associated with needleleaf conifers
  • a west-coast phenomenon, typical of north coast of California and Oregon

Suborder Xerults occur in the same area, but have less OM

Suborder Aquults have an aquic moisture regime

Stop: Pygmy Forest (See the separate handout for this stop)

series properties geographic setting distribution & extent
Blacklock
Sandy, mixed, isomesic, ortstein & shallow Typic Duraquods
poorly drained -- shallow to an ortstein pan, formed in sandy marine sediments

A very strongly acid
E
Bh
Bsm
C

marine terraces. They are usually in depressions or flats between low ridges or hummocks coastal marine terraces of southern Oregon and northern Californiaspodosols.jpg (14702 bytes)
Caspar
Fine-loamy, mixed, isomesic Typic Palehumults
very deep, well drained soils formed in marine sediments

Oi
E1
E2
Bt1
Bt2
Bt3 strongly acid (pH 5.1)

marine terraces;

redwood, doug-fir, bishop pine, tanoak

northern coastal California; not extensive
Noyo
Fine-loamy, mixed, isomesic Typic Albaquults
O1
A1
A21
A22
B2t very strongly acid (pH 4.6)
C
gently sloping, marine terraces; on dunes  

After this extended stop, we'll continue north to Fort Bragg, then take Highway 20 E into Jackson State Demonstration Forest, where we camp some years. We'll look around a bit at the forest soils here, then continue east on Hwy 20. Soils in these conifer forested mountains are dominated by alfisols (udalfs, ustalfs and xeralfs, depending on the moisture regime) and inceptisols (ustepts on the coast and ochrepts further inland). Inceptisols seem to result primarily on steeper slopes or on alluvial terraces (Gschwend series for example). Land use is forestry, primarily aimed at redwood and Doug-fir. In redwood forests at relatively low elevation (<1000'), soils such as Vandamme Haplohumults and many hapludalfs such as the Hotel series occur.

series properties geographic setting distribution & extent
Vandamme
Clayey, mixed, isomesic Typic Haplohumults
deep, well drained soils formed in material weathered from sandstone or mudstone marine terraces and upper sideslopes of hills and have slopes of 2 to 75 percent. Redwood, doug-fir, etc. Northern coastal California. Soil occurs in the zone of strong marine influence. The series is not extensive
Hotel
Loamy-skeletal, mixed, isomesic Ultic Hapludalfs
moderately deep, well drained soils that formed in material weathered from sandstone mountains. Slopes are 30 to 100 percent. Elevation is 10 to 800 feet. Redwood, doug-fir, etc. udalfs.jpg (12851 bytes)Northern coastal California. The series is moderately extensive

As we get away from coastal summer-fogdrip environments, udalfs give way to ustalfs and eventually xeralfs (decreasing moisture gradient, especially in summer). A typical ustalfs complex is Ornbaun-Zeni-Yellowhound:

series properties geographic setting distribution & extent
Ornbaun
Fine-loamy, mixed, isomesic Ultic Haplustalfs
deep; developed on sandstone; reddish yellow subsoil in mountains; 200 to 2,500 feet Northern coastal California. The series is moderately extensive
Zeni
Fine-loamy, mixed, isomesic Ultic Haplustalfs
moderately deep; developed on sandstone; light yellowish brown subsoil in mountains;
Elevations are 200 to 2,500 feet; Doug-fir, redwood, tanoak, etc.
Northern coastal California. The series is moderately extensive
Yellowhound
Loamy-skeletal, mixed, isomesic Ultic Haplustalfs
deep; developed on sandstone in mountains; Doug-fir, etc.
200 to 2,500 feet
Northern coastal California. The series is moderately extensive

Before Willits, forests gives way to oak woodlands. The Hopland-Witherell-Squawrock complex of haploxeralfs and xerepts (shallower soils) are typical for this type of environment -- haploxeralfs are one of the most common soils found in oak woodlands. On south-facing slopes, the Yorkville-Yorktree-Squawrock association of argixerolls and haploxeralfs come into play, as general soil map unit.

series properties geographic setting distribution & extent
Hopland
Fine-loamy, mixed, mesic Typic Haploxeralfs
moderately deep, well drained soils formed in material weathered from sandstone or shale hills and mountains and have slopes of 9 to 75 percent; mean annual precipitation is 42 inches; Oak woodland Northern California in the Coast Range. The soils are moderately extensive
Witherell
Loamy, mixed, thermic Lithic Haploxerepts
shallow, somewhat excessively drained soils formed in material weathered from sandstone hills and mountains. Slopes are 5 to 75 percent. Elevations are 300 to 4,000 feet; annual grasses. not extensive
Squawrock
Loamy-skeletal, mixed, thermic Mollic Haploxeralfs
moderately deep, well drained soils formed in material weathered from sandstone or graywacke. Usually on south or west facing slopes, on hills and mountains and have slopes of 15 to 75 percent. annual grasses. "
Yorkville
Fine, mixed, thermic Typic Argixerolls
very deep, well drained soils that formed in material weathered from chloritic schist Slopes are 5 to 75 percent, are unstable, complex, and are characterized by slips, slides, hummocky relief, sag ponds steep and springs. The soils formed in material weathered from chloritic schist intermixed with other sedimentary and metamorphic rocks. The underlying material is commonly altered from occurring in fault zones. It is locally know as "gouge material". Northern California in the Coast Range. The soils are moderately extensive.
Yorktree
Fine, mixed, mesic Ultic Argixerolls
deep, well drained soils formed in material weathered from graywacke, shale, siltstone or sandstone on ridgetops and sideslopes of hills and mountains and have slopes of 15 to 75 percent. Vegetation is Oregon white oak, California black oak, blue oak, live oak, poison-oak, pacific madrone, Douglas-fir, blue wild rye, wild oats, dogtail and tarweed. mean annual precipitation is about 42 inches Northern California in the Coast Range. The soils are not extensive

Continue on Hwy 20 as it follows U.S. 101 south at Willits. Valley soils here and near Redwood Valley originally developed on grasses and chaparral, and now are used for vineyards, rangeland, watershed, and homes, are typified by the series Pinole, Yokayo, and Redvine series.

Series properties geographic setting distribution & extent
Pinole
Fine-loamy, mixed, thermic Ultic Argixerolls
very deep, well drained soils formed in alluvium on terraces and have slopes of 0 to 30 percent; annual precip 32-50"; hot dry summers Northern California in the Coast Range. The soils are not extensive
Yokayo
Fine, mixed, thermic Typic Palexeralfs
deep, well drained soils formed in material weathered from old alluvium on old dissected terraces and have slopes of 0 to 30 percent; "
Redvine
Fine, mixed, thermic Ultic Palexeralfs
deep, well drained soils formed in old alluvial material; developed in grasses and chaparral dissected terraces and have slopes of 2 to 30 percent; Northern California in Coast Range valleys. The soils are not extensive

Watch for the Clear Lake turnoff for Hwy 20 E. Chaparall and grassland soils are either xerepts, xerorthents (even more eroded) or xerolls (argixerolls on serpentinitic Henneke soils).

Continue east on Hwy 20. In the Mayacama Mountains to the south, north-facing slopes -- with decreased moisture loss and haploxeralf soils -- stand in contrast to south-facing slopes where greater evaporative loss supports chaparral and thinner xerepts.

Possible brief stop: Cold Creek Valley -- The Ancestral Drainage of Clear Lake The Cold Creek valley is also significant to the history of the Clear Lake area, for this was once the route of a stream that drained the Clear Lake valley; thus the area once drained directly to the Pacific via the Russian River. Sometime within the last few thousand years, a massive landslide blocked this drainage route, and Clear Lake was impounded. It now drains over a basaltic lava step into Cache Creek and the Central Valley.

Cold Creek valley soils: Along the terraces and flood plains are Talmage haploxerolls, with some fluvent-like properties, and very gravelly. These may relate to a former larger stream occupying this valley. Other soils are Cole loam, that we'll also see at Clear Lake. Hillsides are Maymen-Etsel-Mayacama complex of dystroxerepts and xerorthents on predominantly eroded chaparral areas, while the thicker soils of oak woodlands and doug-fir forests are dominated by haploxeralfs and palexeralfs, as typified by the Hopland-Sanhedrin-Kekawaka complex.

Series properties geographic setting distribution & extent
Talmage
Loamy-skeletal, mixed, thermic Fluventic Haploxerolls
No B horizon. very deep, somewhat excessively drained soils formed in alluvium. gravelly sandy loam; Coarse fragments average 35 to 90 percent on alluvial fans, terraces, and floodplains and have slopes of 0 to 9 percent.mean annual precipitation is about 40 inches Small extent: valleys in Mendocino and Lake Counties. Used for irrigated crops, dryland grain, pasture, livestock grazing and urban land. Vegetation is annual grasses, shrubs, forbs, with scattered oaks
Cole
Fine, mixed, thermic Pachic Argixerolls
Bt horizon; very deep, somewhat poorly drained soils that formed in alluvium on river tarraces, basins, flood plains, or on alluvial fans with slopes of 0 to 5 percent. Uncultivated areas have oak-grass vegetation with some shrubs and forbs. Used mostly for production of orchards, vineyards, truck crops, and irrigated pasture. North coastal counties, California. The soils are moderately extensive
Maymen
Loamy, mixed, active, mesic Lithic Dystroxerepts
shallow, somewhat excessively drained; on sandstone, shale, or conglomerate on mountains and have slopes of 5 to 100 percent; elevations of 400 to 4,250 feet; Used mainly for watershed, wildlife habitat and recreation. Vegetation is usually open stands of chaparral consisting of chamise, manzanita, several species of ceanothus, several species of scrub or dwarf oak, and scattered small trees in protected sites. Coast Ranges and western slopes of the Sierra Nevada of California. The soils are extensive.
Etsel
Loamy-skeletal, mixed, active, nonacid, mesic Lithic Xerorthents
depth to bedrock 4-14"; no B horizon. many rock fragments; very shallow or shallow, somewhat excessively drained soils;
on mountains. Slopes are 15 to 85 percent. Elevation is 1,000 to 6,000 feet. chaparral. on mountains. Slopes are 15 to 85 percent. Elevation is 1,000 to 6,000 feet.
Mayacama
Loamy-skeletal, mixed, active, mesic Typic Dystroxerepts
15 to 25 percent clay and contains 35 to 60 percent rock fragments. Base saturation (NH40Ac) is 25 to 60 percent south & west facing slopes. Natural vegetation includes interior live oak, California laurel, California nutmeg. knobcone pine, scrub oak, California black oak, and sparce Douglas-fir. Coast Range of Northern California. The series is not extensive.
Kekawaka
Fine, kaolinitic, mesic Ultic Palexeralfs
Thick reddish yellow Bt horizon. very deep, well drained soils formed in material weathered from sedimentary rocks.

Mineralogy is more than one half tabular hallosite and gibbsite

on hills and mountains. Slopes are 2 to 75 percent. Natural vegetation is Douglas-fir, ponderosa pine, sugar pine, California black oak, Pacific madrone, and manzanita. Used for timber production. average annual precipitation is 35 to 60 inches Coast Range of northern California. The series is not extensive.
Great Group Haploxeralfs
  • haplo- thin, or poorly formed, "minimum horizon" -- at minimum of range for suborder.
  • 'haplo-' prefix is common in residual soils of California, probably due to high erosion rates, limited time of formation.

A short ways into Lake County, we'll pass by Tule Lake, which is cultivated for wild rice (actually not really rice) -- the lake level is maintained seasonally for this production. Tule Lake soils are Tulelake fluvaquents. Hillsides continue as xerepts with chaparall and haploxeralfs with oaks and foothill pines.

series properties geographic setting distribution & extent
Tulelake
Fine, smectitic, nonacid, thermic Aeric Fluvaquents
very deep, poorly drained soils formed in lacustrine deposits;
Ap 0-10"
C
Ccal (carbonate)
reclaimed former lake basin In the Clear Lake Basin, Lake County, California. The series is not extensive.

Just past Tule Lake, we'll take Hwy 29 to go around the west side of Clear Lake. Right at the turn we're surrounded by cultivated Lupoyoma Haploxerolls.

series properties geographic setting distribution & extent
Lupoyoma
Fine-silty, mixed, thermic Cumulic Ultic Haploxerolls
cumulic properties; mostly protected by dikes and levees on floodplains; 0-2 % slopes;

used for pear, walnut and wine grape production

Valleys of the Coast Range of Northern California. The soils are not extensive

WEST SIDE OF CLEAR LAKE STOPS:

We continue this typical xeralfs theme dominated by haploxeralfs and somewhat more developed palexeralfs, both common in oak woodlands of California. The Manzanita series of palexeralfs, which are cultivated for walnuts on the flatter slopes, and used for vineyards home sites on steeper slopes, become prominent on terraces near Lakeport. Past Lakeport we pass through some basin soils: the Cole and Clear Lake series of argixerolls and aquerts, used for orchards and vineyards, often requiring drainage. Especially on Cole soils, a history of fluctuating river channels are indicated by frequent stream deposits at the surface and in subsoil lenses. Also in this area, especially near stream crossings (e.g. Adobe Creek, Kelsey Creek), are frequent Still series, similar to Lupoyama above in being cumulic alluvial soils.

Series properties geographic setting distribution & extent
Manzanita
Fine-loamy, mixed, thermic Ultic Palexeralfs
very deep, well drained soils formed in alluvium terraces -- possibly related to old lake levels Clear Lake Basin in Lake County, California. The series is not extensive
Cole
Fine, mixed, thermic Pachic Argixerolls
Bt horizon; very deep, somewhat poorly drained soils that formed in alluvium on river terraces, basins, flood plains, or on alluvial fans with slopes of 0 to 5 percent. Uncultivated areas have oak-grass vegetation with some shrubs and forbs. Used mostly for production of orchards, vineyards, truck crops, and irrigated pasture. North coastal counties, California. The soils are moderately extensive
Clear Lake
Fine, smectitic, thermic Xeric Endoaquerts
very deep, poorly drained soils that formed in fine textured alluvium derived from sandstone and shale basins and in swales of level drainageways clearlake.jpg (29291 bytes)In small valleys of the Coast Range and along the San Joaquin and Sacramento Valleys. The soils are moderately extensive
Still
Fine-loamy, mixed, thermic Cumulic Haploxerolls
cumulic profile; buried horizons on flood plains and alluvial fans; 0-30% slopes; used for orchards, vineyards, etc. Other than here: valleys of the south half of the Coast Range in California. Established in San Luis Obispo. The soils are inextensive.

Past Kelseyville, we'll see Mt. Konocti, a 450,000 Ma composite cone on the left. On it have developed a series of haploxeralfs. Shortly past we'll get to examples of a series of soils with significant obsidian in their makeup -- the Glenview-Arrowhead-Bottlerock complex.

series properties geographic setting distribution & extent
Glenview
Fine, halloysitic, mesic Ultic Palexeralfs
very deep, well drained soils formed in material derived from obsidian and pyroclastic materials hills with slopes of 2 to 50 percent; used mainly for cropland producing walnuts, timber production, watershed and wildlife habitat Obsidian flows in the Clear Lake volcanic field in Lake County, California. The soils are not extensive.
Arrowhead
Clayey-skeletal, mixed, mesic Ultic Haploxeralfs
moderately deep, well drained soils formed in material weathered from obsidian. Mineralogy is influenced by amourphous material; lithic contact on volcanic flows; Used mainly for watershed and wildlife habitat. Natural vegetation consists of chamise, manzanita, and scrub oak Clear Lake volcanic field, Lake County, California. The series is not extensive.
Bottlerock
Loamy-skeletal, mixed, mesic Ultic Palexeralfs
deep, well drained soils formed in material derived from obsidian on hills and dissected volcanic flows "

At Lower Lake, turn left on Hwy 53 and return to Hwy 20. Before continuing east, we'll take a brief side trip by going west on Hwy 20. In just a few miles look for a small sign for St. Anthony's church on the left, and stop near the quarry.

Hwy 20 alternate (in case we're short on time). The north shore of Clear Lake is heavily built up with summer homes, but the hills continue to be covered with haploxeralfs and palexeralfs, with an occasional haploxerolls thrown in, especially on metabasalts at the Narrows and at Upper Lake, where mollisols are developed in alluvium on floodplains of inflowing streams. Other associated soils of the floodplains and deltas are Clear Lake clay Pelloxererts and fluvaquents.

Past Clearlake Oaks, look for cinder cones on both sides of the road. We'll attempt to turn right onto a road leading to St. Anthony's Church, and stop near the quarry.

Stop: Vitrands - Cinder Land Complex

Pleistocene and Holocene volcanism has been significant to the Clear Lake area. Mt. Konocti, a composite cone which produced both rhyolitic tephra and basaltic lava flows as recently as the last 5000 years, dominates the landscape. These two tephra cones are probably younger, but their apparent age is younger than their actual age due to the high permeability of the loose basaltic cinders. Note the red color from iron oxides (remember that basalt is composed of iron-rich minerals).

Continue east on Hwy 20. The only significant soil diversity until we reach the summit area is when we pass through a segment of Long Valley, where the Still-Lupoyama Association of haploxerolls are developed on the flood plain and xerofluvents and riverwash are found on recent deposits -- note gravel pits. At the summit, we pass into Lake County. Steep slopes produce high erosion rates and thinner soils. Millsholm Lithic Haploxerepts is one example, though good old haploxeralfs dominate. This area is primarily used for grazing, wildlife habitat, and watershed.

Continuing E on 20, we start to descend the Coast Ranges, and encounter decreasing precipitation and drier soils, however there will be several parent-material controlled changes along the way. When the road crosses over to the Bear Creek drainage, we find extensive Henneke stony clay loam Lithic Argixerolls developed on serpentine. Beyond this, one of the clearer examples of stratigraphic bedding can be seen in rocks of the Great Valley Sequence, which extends under the sediments deposited more recently in the Central Valley. The road follows Salt Creek Valley, on either side of which are residual soils such as Altamont Typic Chromoxererts, Los Osos Typic Argixerolls, and Contra Costa Mollic Haploxeralfs, developed on sandstones and shales, then passes through a gap in Cortina Ridge towards the Central Valley, where we descend the alluvial fans and terraces of the western margin of the Central Valley, where Hillgate loam & clay loam Typic Palexeralfs are developed in association with an original oak woodlands community.

Stay on 20 through Williams. 3.5 miles before Williams, somewhat more well-drained conditions have increased the chroma of the clay soils, and here the Myers clay Aridic Haploxererts are found. West of Colusa on Hwy 20, pass through various endoaquerts (e.g. Willows clay).

series properties geographic setting distribution & extent
Henneke
Clayey-skeletal, magnesic, thermic Lithic Argixerolls
serpentinitic; depth to serpentinite is 10-20". Rock outcrops, stones, and cobbles are common and occupy 5 to 60 percent of the surface. mountainous uplands; Used mostly for wildlife and watershed. The principal native plants are scattered oaks, Foothill pine, Coulter pine, cypress, and shrubs such as leather oak, whiteleaf manzanita, muskbrush, and toyon. Grasses are sparse, usually squirreltail and a few annuals. Coast Ranges, foothills of the Sierra Nevada and Klamath Mountains of California. The soils are extensive
Altamont
Fine, smectitic, thermic Aridic Haploxererts
deep, well drained soils that formed in material weathered from fine-grained sandstone and shale; slickensides, cracks. on gently rolling to very steep uplands; Used for grazing and dry farmed grains, mainly barley. The principal plants are annual grasses, forbs, and scattered oak trees In the Coast Range in central and southern California and the Sutter Buttes. The soils are extensive.
Contra Costa
Fine, mixed, superactive, thermic Mollic Haploxeralfs
moderately deep, well drained residual soils foothills & mountains; Vegetation is mostly trees and annual grasses Foothills and mountainous ranges of the east-central and northern coast ranges, California. The soils are moderately extensive.
Hillgate
Fine, smectitic, thermic Typic Palexeralfs
very deep, well to moderately well drained soils that formed in alluvium on nearly level to moderately sloping old terraces at elevations of 15-2,000 feet; precipitation varies from 14 to 30 inches; grasses and valley/blue oaks West side of Sacramento Valley and Coast Range valleys, soils are of moderate extent.

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series properties geographic setting distribution & extent
Myers
Fine, smectitic, thermic Aridic Haploxererts
grayish brown and dark brown clay A horizons, and brown calcareous C horizons. nearly level alluvial fans. Average annual precipitation is 15 to 30 inches. Used for dry farmed grain, irrigated row, field crops and rice This soil occurs on the west side of the Sacramento Valley and in the interior valleys of the Coast Range of California. The series is of moderate extent.
Willows
Fine, smectitic, thermic Sodic Endoaquerts
very deep, poorly to very poorly drained sodic soils formed in alluvium in nearly level basins in intermountain valleys and large valleys. rice, sugar beets and safflower; original vegetation was saline-sodic tolerant plants On the west side of the Sacramento and San Joaquin Valleys and intermountain valleys of the Coast Range, California. The soils are moderately extensive
Brentwood
Fine, smectitic, thermic Typic Haploxerepts
A & minimal Bt horizons, in valley fill from sedimentary rocks on nearly level to gently sloping fans. They occur at elevations of 40 to 400 feet. The climate is dry
subhumid mesothermal, with hot dry summers, and cool moist winters. Mean annual rainfall is 12 to 20 inche
Valleys of the Coast Range and west side of the Sacramento and San Joaquin Valleys. The soils are moderately extensive.
Yolo
Typic Xerorthents
thick grayish brown, neutral silt loam A horizons and brown and pale brown mildly alkaline silt loam C horizons.  Yolo soils have less than 35 percent clay and less than 15 percent fine sand or coarser. nearly level to moderately sloping alluvial fans. The soils formed in fine-loamy alluvium derived from sedimentary formations West site of Sacramento Valley, central California, and in the valleys of the California Coast Range. The series is extensive.

Stay on Hwy 20 through Colusa. Colusa clay loam Natrixeralfs are found 2 miles south of Colusa, and are characterized by black alkali in profiles. Near the intersection with Hwy 45, older, imperfectly drained soils with alkali and gypsum salts in the profiles indicate Marvin clay loam Aquic Haploxeralfs, and another soil used for rice cultivation due to nearly impermeable clay in lower horizons.

series properties geographic setting distribution & extent
Colusa
Coarse-loamy, mixed, superactive, thermic Typic Natrixeralfs
very deep, somewhat poorly drained soils that formed in alluvium on nearly level flood plains with slopes of 0 to 2 percent; mean annual precipitation is 16 inches

Pasture, both dryland and irrigated saltgrass; Natural vegetation is salt grass and other halophytic plants

Flood plain of the Sacramento River in the lower Sacramento Valley. The soils are not extensive.
Marvin
Fine, smectitic, thermic Aquic Haploxeralfs
grayish brown, mottled, slightly acid, silty clay loam A horizons, mildly alkaline transition horizons and dark grayish brown, mildly alkaline, silty clay Bt horizons and light olive brown, calcareous B3 and C horizons. on nearly level flood plains at elevations of 10 to 100 feet under annual grasses and forbs.

Natural vegetation is annual grasses and forbs, and open stands of valley oaks . Saline-alkali tolerant plants are in alkali areas.

Central Sacramento Valley, California. The soils are inextensive.

Use: Irrigated and dry cropland and pasture. Main crops are grain, field crops, sugar beets, alfalfa and rice.

Just before the Sacramento River crossing near Sycamore are soils mapped as Sycamore loam & clay loam Mollic Endoaquepts. Though these are only mapped in the older Colusa County soil survey, these are distinguished from the more common Columbia soils by the presence of a calcareous subsoil in the Sycamore. We may make a stop here to see if we can detect the presence of alkali described in the Sycamore profile. On the east side of the river, recent alluvium dominates, and Columbia Xerofluvents and Nueva loam Fluventic Haploxerolls are the dominant soils.
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series properties geographic setting distribution & extent
Sycamore
Fine-silty, mixed, nonacid, thermic Mollic Endoaquepts
grayish brown, slightly acid, slightly clay loam A horizons; grayish brown and light brownish gray, distinctly mottled, mildly to moderately alkaline, silt loam B horizons; and stratified light brownish gray and pale brown mottled loam, fine sandy loam and loamy fine sand calcareous C horizons. on nearly level flood plains at elevations of 10 to 100 feet. The soils formed in mixed sedimentary alluvium; 15 to 20 inches precip.

Natural vegetation consists of annual grasses and oak.

The flood plain of the Sacramento River and its tributaries in central California. The series is of moderate extent.

used for orchard, row, truck, and field crops excluding rice.

Columbia
Coarse-loamy, mixed, superactive, nonacid, thermic Oxyaquic Xerofluvents
very deep, moderately well drained soils formed in alluvium on flood plains with bar and channel topography in some natural areas, and natural levees and have slopes of 0 to 8 percent

Vegetation consists of a fairly dense cover of oaks, cottonwoods, willows, vines, shrubs and grasses near stream channels, but more open away from the channels.

These soils occur in the central valley of California. The soils are moderately extensive

These soils are used for irrigated hay, small grain, orchard and row crops.

Nueva
Fine-loamy, mixed, thermic Fluventic Haploxerolls
very deep somewhat poorly drained soils formed in alluvium on floodplains and have slopes of 0 to 2 percent Southeastern part of Sacramento Valley. Soils are not extensive.

These soils are used for irrigated orchards, small grains and row crops.

Likely Stop: Clarks Farm north of Colusa. See map of area. Follow directions (not given here).

Side Possible Stop : Soils on Old Terrace Deposits.

Uplands to the west of Capay Valley are dissected alluvial fan deposits of late Pliocene age, the Tehama and the overlying Red Bluff Formations, the former dated by a basal volcanic tuff at 3.3 Ma (million years BP), around the same time of the formation of the Sutter Buttes as a local volcanic dome. In the Capay Hills (where we should be standing), Balcom silty clay loam Xerorthents are developed on steeper slopes eroded from the compacted but uncemented Tehama Formation sediments. The Dunnigan Hills to the east of here are also eroded from the Tehama Formation; soils in these hills are rich in clays, and mapped as either Sehorn clay Entic Chromoxererts (A/C), with an olive-gray (5Y 5/2) subsoil, or are in a complex with Balcom soils, with Sehorn soils occupying deeper, moister footslope sites.

The original gravelly surface of the Red Bluff Formation, possibly Pleistocene in age, is preserved as scattered terrace remnants. Where preserved, soils on this surface are quite old, and have developed prominent Bt horizons. Positas gravelly loam Mollic Palexeralfs, with a yellowish-red (5YR 4/6) Bt horizon and dark red (2.5 YR 3/6) clay films, dominates these old terrace soils. In spite of the gravelly loam texture, permeability is very slow due to the heavy clay Bt.

Stop: Capay Chromoxererts

If we have time, we may take the Tarke Road turnoff to the south (right), road V652, and stop about one mile south, to see these chromoxerts.... Continuing on 20, just past the Sutter Bypass, we'll cross an alluvial fan composed of andesite, lahar, and sand deposits from the Tertiary-age volcanics of Sutter Buttes; on these deposits, the Olashes Haploxeralfs have developed -- and soils are better drained, favoring orchard crops.

We then descend to much more poorly drained soils of the Oswald-Gridley-Subaco Association -- xererts and argixerolls widely used for rice and prunes. Outside of Yuba City, we again see evidence of the orchard crops (walnuts, peaches, prunes, almonds, kiwis) typically associated with the well-drained alluvial terrace soils: haploxerolls of the Conejo-Tisdale Association.; tomatoes, dry beans and melons are also grown. Stay on 20 through Yuba City, developed on these terrace soils. Crossing the Feather River, where Columbia fine sandy loam Aquic Xerofluvents are developed on recent alluvium.

Continue through Marysville on 20. This part of Yuba County is frequented by mine tailings, especially along the Yuba River. The road gradually climbs alluvial fan deposits of the eastern Central Valley margin. Watch for the turn, before the Yuba River crossing, for the Sierra Foothills Field Camp, where we'll be staying.

Soils of the Sierra Foothills Field Camp

series properties geographic setting distribution & extent
Auburn xerepts shallow soil on eroded sites, with A & Bw horizons on lithic contact at 20", on metabasic or metasedimentary rock such as amphibolite schist, greenstone schist, or diabase. foothills with slopes of 2 to 75 percent.  Elev: 125 to 3,000 feet. Climate: subhumid with hot dry summers and cool moist winters. Precip: 20 to 40 inches.   Rock outcrops are common. Lower foothills of the Sierra Nevada. Extensive.
Sobrante Mollic Haploxeralfs moderately deep soils with A & Bt, on basic igneous or metamorphic rocks: amphibolite schist, diabase, andesite, or basalt. foothills with slopes of 2 to 75 percent. Elev:  125 to 3,500 feet. Climate: subhumid with hot dry summers and cool moist winters. Precip: 20 to 40 inches. Coast Range & Sierra Nevada foothills
TimbuctooRhodoxeralfs on mafic metavolcanic rock

Next Morning or as an afternoon sidetrip: We'll continue on 20 towards Nevada City, ascending through the oak-woodland foothills characterized by haploxeralfs. Past Rough & Ready, we'll start to ascend the lower slopes of the Sierra, and as precipitation increases we'll continue to find forested haploxeralfs, but we'll also find soils of lower base saturation, e.g. haplohumults, except on volcanic deposits where vitrands may occur.

Possible Side Trip into Sierra Nevada: on Hwy 20, continue up to Truckee. Increasing frequency of Sierra batholith granitic rocks, with scattered volcanic deposits (e.g. lahar deposits) and some peaks. Thin xerepts on granite, frequent rounded boulders and domes ­result of dilatation & exfoliation. Vitrands on volcanic materials. Near crest, colder climates create Cryochrepts, Cryumbrepts, Cryands. NE-facing escarpments have evidence of recent glacial activity. Stony soils developed on glacial moraine deposits, gravelly alluvium (proglacial sediments), bare rock and rubble characterize this area.
series properties geographic setting distribution & extent
Aiken
Xeric Haplohumults
on mafic volcanic rock, especially tuff breccia 1200 to 5000 feet; ponderosa pine. extensive in Sierra & Cascades
Side Trip to hydraulic mine.

Hydraulic mining of deposits of Tertiary gravels along the ancestral Yuba River are well illustrated here. The tailings and severely eroded hillsides have obviously little if any soil developed on them in the relatively short period of time since hydraulic mining ceased, partly due to the resulting instability of the sediments left behind. Interestingly the soils being mined are quite well developed -- Horseshoe Haplohumults can be found in unmined patches. We'll have a look.

Return to Nevada City and Grass Valley, and follow Hwy 49 S towards Auburn. Soils are dominated by haploxeralfs, with xerepts on more eroded sites, and haplohumults and haploxerults on more stable surfaces. Serpentinite outcrops (such as just before Elders Corner) sometimes produce Henneke Lithic Argixerolls, since they don't support thick forest cover, but rather have been grass or scrub-covered, but soils are unstable and outcrops frequent. Xerofluvents and riverwash occur at stream crossings (especially Bear River, impacted by hydraulic mining upstream). Continue on 49 to Placerville -- well-developed residual soils continue to dominate.


Return to Hwy 49, and continue S towards Jackson. Road descends a bit to the foothills again: xerepts and xeralfs dominate on the oak woodland soils. At Hwy 16, we'll go W for a half mile, then take a left turn towards Ione. Professor will find his way to Apricum Hill, where we'll stop.

Stop. Ione Formation.

Brief hike gets us to Apricum Hill, where a fascinating tropical paleosol has been exhumed. Not officially an Oxisol, since it is not a current soil development, it still is a highly acidic soil with abundant kaolinite with a lateritic layer; soils developed on it seem to be classified as Amador Xerepts. Ione Manzanita (Arctostaphylos myrtifolia) and Ione Wild Buckwheat (Eriogonum apricum) are endemic to this formation. This is believed to be a Tertiary soil development, developed under a tropical climate.

Return to Ione, and follow Hwy 104 W towards the delta. Near Clay, we are on terrace soils again, starting with the Redding gravelly loam Abruptic Durixeralfs, with an iron-silica hardpan, characterized by "hogwallow" microrelief, and fairly acid (pH < 5.3). On higher hills are Pentz gravelly loam Vitrands on rhyolitic tuff, with a more neutral reaction. The road crosses various drainages, but continues to descend onto the lower terrace and basin soils.

Stop. Iron Hard Pan Soils.

Alluvial terraces formed during the Pleistocene as Sierra Nevada alluvial fans are found along the entire eastern margin of the Central Valley, except where interrupted by recent river channels and floodplains. An iron-silica hardpan has developed as shallow groundwater seepage and evaporation has concentrated these minerals within the soil. These soils have relatively low agricultural value, though some are planted with grain and clover, and are usually used for rangeland & pasture. We'll try to find a good spot to check these out.

Cross under Hwy 5 and take Twin Cities Road towards Locke and Walnut Grove. Low terraces are composed of Glann Aeric (Haplaquepts) and San Joaquin loam (Typic Durixeralfs) with dark-gray Alamo adobe clay Typic Duraquolls in flat depressions. At the Cosumnes River floodplain, we briefly see basin soils such as the Columbia Xerofluvents we remember from the valley crossing farther north.

We now are in an area of delta soils, comprised of a scattering of more alluvial sediments producing Columbia Aquic Xerofluvents, more peaty mucks classified as haplaquolls, and a few true histosols. We'll find our way to Isleton, then Rio Vista on Hwy 12. Before Rio Vista, we'll briefly cross low terraces with haploxeralfs developed on fine-textured weakly-cemented sedimentary rock of alluvium. Continue on Hwy 12 to Grizzly Island Road south of Fairfield.

Stop : Delta Histosols

The Sacramento-San Joaquin Delta is of course where these two rivers have slowed significantly and thus deposited sediments eroded from the Sierra Nevada and Coast Ranges. Because of the subsiding nature of the Central Valley, the original extent of the delta might be considered to be much greater than its size today -- certainly there were significant areas of riparian wetlands extending through much of both parts of the valley. The result has been extensive soils formed on fine alluvium, and frequent wetlands. Wetlands soils are usually of two types, the most common being muck -- composed of a mixture of mud and organic material and mapped as haplaquolls and fluvaquents. Peat, mapped as Histosols, is composed primarily of organic material, and is somewhat less common, but is here we have an example. The soils here are clearly an accumulation of peat formed from imperfectly decomposed tidal marsh vegetation. Unfortunately, they are only mapped as "histosols" -- let's see if we can identify whether it's fibrists, hemists, or saprists.histosols.jpg (9198 bytes)

Suborder Aquolls
  • Louisiana bayous
  • Red River basin along Minnesota-North Dakota border -- glacial lake bed.

We conclude the trip by heading home on I-80. Along the way, typical soils include a mixture of haploxerolls and haploxeralfs on hills of more consolidated sedimentary and igneous rocks (granitic and metabasic) with occasional xererts on clay-rich sedimentary rocks, aquolls developed in alluvium on the "flats" of the Oakland-Richmond corridor, and natrixeralfs, fluvaquents and fill along the bay front.