U.S. Department of the Interior

U.S. Geological Survey

Data Series 902

Prepared in cooperation with the U.S. Army Corps of Engineers, Sacramento District

Digital Geospatial Presentation of Geoelectrical and 

Geotechnical Data for the Lower American River and 

Flood Plain, East Sacramento, California
Cover. View of the three-dimensional framework for the lower American River.
Digital Geospatial Presentation of 

Geoelectrical and Geotechnical Data for 

the Lower American River and Flood Plain, 

East Sacramento, California

By Lyndsay B. Ball, Bethany L. Burton, Michael H. Powers, and Theodore H. Asch

Prepared in cooperation with the U.S. Army Corps of Engineers, Sacramento 

District

Data Series 902

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

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Suggested citation:

Ball, L.B., Burton, B.L., Powers, M.H., and Asch, T.H., 2014, Digital geospatial presentation of geoelectrical and geotechnical data for the lower American River and flood plain, east Sacramento, California: U.S. Geological Survey Data 

Series 902, 12 p., http://dx.doi.org/10.3133/ds902.

ISSN 2327-638X (online)
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................1

Methods...........................................................................................................................................................3

Presentation of Results.................................................................................................................................4

References Cited............................................................................................................................................6

Appendixes .....................................................................................................................................................7

Figures

1. Location of the lower American River study reach and associated geophysical and

boring data.....................................................................................................................................2

2. View of the three-dimensional framework project in Encom Discover PA Viewer

software .........................................................................................................................................5

Tables

1. Summary of geoelectrical data presented in this digital release ........................................3

2. Definition of Universal Soil Classification System symbols ..................................................4

3. Digital data organization for the lower American River geophysical framework 

and source data ............................................................................................................................4
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83)

Elevation, as used in this report, refers to distance above the vertical datum.
Digital Geospatial Presentation of Geoelectrical and 

Geotechnical Data for the Lower American River and 

Surrounding Flood Plain, East Sacramento, California

By Lyndsay B. Ball, Bethany L. Burton, Michael H. Powers, and Theodore H. Asch

Abstract

To characterize the extent and thickness of lithologic 

units that may have differing scour potential, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of 

Engineers, has performed several geoelectrical surveys of the 

lower American River channel and flood plain between Cal 

Expo and the Rio Americano High School in east Sacramento, 

California. Additional geotechnical data have been collected 

by the U.S. Army Corps of Engineers and its contractors. 

Data resulting from these surveys have been compiled into 

similar database formats and converted to uniform geospatial 

datums and projections. These data have been visualized in 

a digital three-dimensional framework project that can be 

viewed using freely available software. These data facilitate a 

comprehensive analysis of the resistivity structure underlying 

the lower American River corridor and assist in levee system 

management.

Introduction

The lower American River corridor in east Sacramento, 

California, serves a variety of functions. The American River 

provides several fundamental ecosystem services, including 

habitat for Pacific salmon (Merz and Vanicek, 1996) and the 

federally threatened elderberry longhorn beetle (Lang and others, 1989). The river and flood plain also serve as popular recreation areas for local residents, providing parks, bike/pedestrian trails, and boating and fishing opportunities. Finally, the 

corridor is a causeway for floodwaters, and the levee system 

defining the modern boundary of the river corridor provides 

critical flood protection for the city of Sacramento and surrounding suburban development. 

The American River levees bound a flood plain underlain 

by a mixed lithology of alluvial and hydraulic mining deposits that vary in thickness but may reach up to 80 ft (Helley 

and Harwood, 1985). Sand deposits have been observed to 

be preferentially prone to scour during floods, whereas some 

lithologic packages in the river channel have been observed to 

resist scour. Scour-prone lithologic packages have the potential to compromise the levee system and require mitigation. An 

improved understanding of the geometry and scour potential 

of major lithologic packages underlying the lower American 

River and its flood plain may facilitate more strategic management of the levee system and the river corridor’s other 

functions.

Traditionally, exploration of lithologic and geotechnical 

properties is accomplished through borehole drilling, allowing subsurface materials to be directly observed, described, 

and tested. Extensive drilling has been conducted on the lower 

American River corridor, resulting in high vertical-resolution 

data sets describing the lithology and stiffness of the sediments. Although types of data are invaluable, their inherently 

one-dimensional nature makes upscaling to a more manageable regional interpretation difficult. Surface geophysical 

data can provide supporting information about the variability 

of subsurface physical properties that may be correlated to 

changes in lithology or scour potential. Borehole data provide 

high-resolution data about the vertical distribution of properties, surface geophysical data can provide supplemental data 

about vertical and lateral variations in physical earth properties. Geoelectrical methods measure the resistivity of the 

subsurface. The resistivity of a given material is controlled primarily by water content and quality, and also by the presence 

of clays or other conductive minerals. Changes in resistivity 

structure therefore reflect changes in porosity/compaction, 

lithologic texture, degree of saturation, groundwater composition, cementation, and degree of weathering/fracturing. 

Purpose and Scope

To assist the U.S. Army Corps of Engineers (USACE) 

with the management of the lower American River levee system, the U.S. Geological Survey (USGS) has completed three 

surface geophysical surveys to explore the resistivity structure 

of the American River flood plain and channel (fig. 1). These 

surveys were conducted on the 5.5-mile reach between Cal 

Expo (near river mile 5.5) and the Rio Americano High School 

(near river mile 11). This reach has been identified by USACE 
2 Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain

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X

EXPLANATION

Water-borne direct-current 

resistivity profile

River mileBoringCapacitively coupled resistivity profileDirect-current resistivity profile

0 5 MILES0 5 KILOMETERS

Base from Farm Service Agency National Agricultural Imagery Program, 2012California State Plane projection, Zone II, in feetNorth American Datum of 1983

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0 5,000 FEET0 1,000 METERS

W

U.S. ROUTE 50

SACRAMENTO

CALIFORNIA

NEVADA

OREGON

ARIZONA

Amer

ci an

River

Sacramento

River

Study area

Cal Expo

California

State

University— 

Sacramento

Campus 

Commons

Golf

Course

Rio Americano

High School

WATT AVENUE

HOWE AVENUE

H STREET

RM5

RM11

Direction of flow

Folsom

Lake

Figure 1. Location of the lower American River study reach and associated geophysical and boring data.
Methods 3

as a priority levee management area. Preceding reports document the methods and results of each survey (table 1; Asch 

and others, 2008; Ball and Teeple, 2013; Burton and others, 

2014). The combined results of these surveys are released in 

this report as digital data in a three-dimensional (3-D) framework that allows geospatial comparison between the geophysical results and available geotechnical and lithologic data. This 

report does not present formal interpretations of these data 

sets. Summary of geoelectrical data presented in this digital 

release. The full reports provide details on the methods and 

results of each survey.

Methods

Geoelectrical data were collected by the USGS during 

three field campaigns between 2007 and 2011 using a combination of techniques that characterize subsurface resistivity (table 1). Galvanic and capacitive resistivity techniques 

consisted of land-based direct-current (DC) resistivity (Asch 

and others, 2008; Burton and others, 2014), water-borne DC 

continuous resistivity profiling (CRP) (Ball and Teeple, 2013), 

and capacitively coupled (CC) CRP (Asch and others, 2008; 

Burton and others, 2014). These data have been included in 

the framework presented in this report. Frequency-domain 

multi-frequency (Asch and others, 2008) and multi-offset electromagnetic (EM) induction data (Burton and others, 2014) 

were also acquired during field surveys. The single receiver 

coil, multi-frequency EM data suffered from low electromagnetic response levels, high ambient electromagnetic noise, and 

large system drifts, all of which precluded useful inversions 

(Asch and others, 2008). Although this would not be as large 

a problem in conductive terrain, the high-resistivity nature of 

the materials underlying the lower American River creates a 

non-ideal environment for using small induction number EM 

profiling systems. Most of the single-frequency, multi-offset 

receiver coil EM data are located along the same profile paths 

as the left bank CC CRP data and do not provide additional 

site coverage. Because the purpose of the framework is to provide a spatially comprehensive and interpretable view of the 

resistivity structure of the study reach using the best-available 

data, the EM data were excluded from the framework.

Resistivity measurements are made by transmitting current into the subsurface and measuring the resulting voltage 

at the ground surface. Traditionally, individual resistivity 

measurements are made using a set of four electrodes (two 

current electrodes and two potential electrodes), known as an 

array, to make a measurement. As larger distances are placed 

between electrodes, the depth of investigation increases. 

Modern resistivity profiling typically uses a large number 

of steel electrodes hammered into the ground and connected 

through multiconductor cables to a digital meter. The meter is 

programmed to switch between many different combinations 

of current and potential electrode pairs, creating a cross section of apparent resistivity measurements. Advanced resistivity 

meters contain multiple data channels, allowing simultaneous 

voltage measurements to be made between potential electrodes 

with various spacings using a single current transmission from 

two current electrodes. Therefore, the resistivity at multiple 

depth intervals can simultaneously be determined. 

When electrical contact with the subsurface can be established without hammering steel stakes into the ground, such as 

by submerging the multiconductor cable in water or developing an electric field through capacitance, data can be collected 

while the electrode array is slowly pulled using the CRP technique. The CRP technique allows rapid data collection with 

high lateral resolution, but this technique has a more limited 

depth-of-investigation and can often be more susceptible to 

site-related noise when compared to traditional resistivity profiling. For these reasons, both CRP and traditional resistivity 

profiling techniques were used at the lower American River.

The data-collection and processing methods and results 

of each survey are discussed in detail in individual reports 

and are briefly summarized here: The 2007 survey focused on 

characterization of the right bank of the flood plain between 

the Campus Commons golf course and the Rio Americano 

High School (Asch and others, 2008). The CC CRP data were 

collected using a single capacitive current dipole cable paired 

with several potential dipole cables towed behind an all-terrain 

vehicle. The CC CRP technique allowed the collection of long, 

shallow resistivity profiles (depth of investigation = 15 to 

45 feet [ft]) that cover nearly the entire length of the study area 

and often include multiple passes along the width of the flood 

plain (fig. 1). These long profiles were supplemented with 

shorter segments of traditional DC resistivity data in selected 

areas to characterize deeper resistivity structure (depth of 

investigation = 60 to 210 ft) and to evaluate the influence of 

urban noise and signal strength in the CC resistivity results. 

Table 1. Summary of geoelectrical data presented in this digital release.

[The full reports provide details on the methods and results of each survey. CC, capacitively coupled; DC, direct-current; river banks are described relative to the 

direction of flow]

Survey date Type of data collected Location Full report

May 2007 CC resistivity, ground DC resistivity Right bank Asch and others, 2008

May–June 2008 Water-borne DC resistivity River channel Ball and Teeple, 2013

June 2011 CC resistivity, ground DC resistivity Left and right banks Burton and others, 2014 
4 Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain

The 2008 survey used a water-borne CRP technique of the 

DC resistivity method to characterize the river channel, 

where data were collected while towing a 13-electrode array 

behind a boat. By using this technique, nearly continuous, 

moderately deep resistivity profiles (depth of investigation = 

65 ft) were acquired along three passes of the American River 

channel (Ball and Teeple, 2013). In 2011, a nearly identical approach to that taken in 2007 (combining CC CRP and 

traditional DC resistivity profiling) was applied to the entire 

left bank and the right bank downstream of the Campus Commons golf course (Burton and others, 2014). 

Data from all surveys were positioned using sub-meter 

accuracy global positioning systems, although heavy tree 

cover in some parts of the flood plain resulted in a loss of 

satellite reception. In these areas, data were interpolated 

between well-positioned locations assuming a uniform CRP 

towing speed. Apparent resistivity measurements from each 

survey were inverted in commercial software using similar 

processing schematics to estimate the heterogeneous resistivity structure and are discussed in detail in the individual 

survey reports (Asch and others, 2008; Ball and Teeple, 2013; 

Burton and others, 2014). To maintain consistency between 

survey years and to insure that the best processing methods 

available were used, CC CRP data from the 2007 right-bank 

surveys were fully reprocessed and inverted to follow the 

same procedures used for the 2011 left bank survey (Burton 

and others, 2014).

To prepare the digital data for this release, inverted resistivity models from each survey were compiled into databases 

specific to each method. A uniform projected coordinate 

system (California State Plane, zone II) and horizontal datum 

(North American Datum of 1983) were applied to all databases. A uniform vertical datum (North American Vertical 

Datum of 1988) was established using a 9-ft resolution grid 

of bare-earth corrected light detection and ranging (lidar) data 

and river bathymetric surveys provided by USACE (Lewis 

Hunter, USACE, written commun., February 2012). The 

integration of these three surveys provides comprehensive 

characterization of the resistivity structure of the study reach.

Extensive boring data have also been provided by 

USACE and include both lithologic and geotechnical data 

(Lewis Hunter and Michael Kynett, USACE, written communs., February and October 2012). Boring data have been 

complied into digital databases and projected into the same 

geospatial coordinate system and datums as the geophysical data. Lithologic materials have been described using the 

Universal Soil Classification System categories commonly 

applied to engineering problems (table 2) (American Society 

of Testing and Materials, 1985). Geotechnical data consist 

of estimations of soil stiffness (N-value or blow count) from 

a variety of methods including cone-penetrometer (CPT) 

and standard-penetrometer (SPT) in-situ testing. For the 

“CF” series of borings, corrected N160 values were used to 

represent the N-value. Data intervals displayed in the framework are limited to the tested interval only, as described by 

the sample length in the original database. Non-numerical 

reported values suggesting that resistance was met, such as 

“R” or high blow counts for intervals less than 6 inches, were 

given an N-value of 150 for visualization. These boring data 

are the foundation for creating meaningful interpretations of 

lithologic and scourability variations in the subsurface using 

the resistivity data. 

Presentation of Results

Data are provided in two formats (table 3). The primary 

format is a 3-D framework project that has been prepared 

using Encom Discover Profile Analyst (PA) software (Pitney 

Bowes, North Sydney, Australia) (3DFRAMEWORK directory). This project provides a geospatially referenced environment where the geophysical and boring data can be viewed, 

zoomed, rotated, and toggled on and off (fig. 2). Encom 

Discover PA Viewer software can be freely downloaded from 

Pitney Bowes (http://www.pitneybowes.com/pbencom/support/

product-downloads.html). Once installed, the project may be 

opened from the viewer program by selecting the AmRiv3DFramework.egs project file. The 3-D visualization can be 

computationally expensive and may take several minutes to 

load on some systems.

Table 2. Definition of Universal Soil Classification System 

symbols (American Society of Testing and Materials, 1985).

Symbol Definition

G Gravel

S Sand

M Silt

C Clay

O Organic matter

P Poorly graded (uniform particle sizes)

W Well-graded (diverse particle sized)

H High plasticity

L Low plasticity

Table 3. Digital data organization for the lower American River 

geophysical framework and source data.

Directory Contents

3DFRAMEWORK Digital framework project and supporting 

files.

SOURCE_DATA Databases of the inverted resistivity profiles 

and boring data in ASCII standard (*.xyz, 

*.csv) and Geosoft Oasis montaj (*.gdb, 

http://www.geosoft.com/) database formats.
Presentation of Results 

5

Figure 2. View of the three-dimensional framework project in Encom Discover PA Viewer software. An explanation of the symbology is provided in appendix 2.

N

WATT AVENUE

Rio Americano

High School

Cal Expo

U.S. ROUTE 50

5,0001,00010025

Resistivity (ohm-meters)

EXPLANATION

Base from Farm Service Agency National Agricultural Imagery Program, 2005California State Plane projection, Zone IINorth American Datum of 1983

Boring
6 Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain

The 3DFRAMEWORK directory (available at http://

pubs.usgs.gov/ds/0902/downloads/3DFRAMEWORK.zip) 

contains many additional source files necessary to run the 

project, and the project session may become corrupted if 

the files in the directory are modified. The databases used to 

generate the framework project are provided in a separate 

directory (SOURCE_DATA directory; available at http://

pubs.usgs.gov/ds/0902/downloads/SOURCE_DATA.zip) and 

described in detail in appendix 1. It is highly recommended 

that these source databases be used to the view the data in 

other software platforms instead of accessing the files stored in 

the 3DFRAMEWORK directory. The resistivity structure as a 

function of depth along the geophysical profiles is given in an 

array matrix format, where indexes are used to match corresponding depth and resistivity values. To facilitate comparison 

of the inverted resistivity profiles to other data beyond the 

geophysical lines, such as borehole lithology or remote sensing data, land-surface elevations in the resistivity profile and 

boring databases have been sampled from the 9-ft-resolution 

lidar-derived digital-elevation model referenced to NAVD88. 

An explanation of the digital data structure and contents 

of this report are in appendix 1. A graphic explanation to 

the symbology used in the framework project is provided in 

appendix 2. 

References Cited

American Society of Testing and Materials, 1985, Classification of soils for engineering purposes: Annual Book of 

ASTM Standards, v. D 2487-83, p. 395–408.

Asch, T.H., Deszcz-Pan, M., Burton, B.L., and Ball, L.B., 

2008, Geophysical characterization of the American River 

levees, Sacramento, California, using electromagnetic, 

capacitively coupled, and direct-current resistivity: U.S. 

Geological Survey Open-File Report 2008–1109, 12 p.

Ball, L.B., and Teeple, A.P., 2013, Characterization of major 

lithologic units underlying the lower American River using 

water-borne continuous resistivity profiling, Sacramento, 

Calif., June 2008: U.S. Geological Survey Open-File Report 

2013–1050, 13 p.

Burton, B.L., Powers, M.H., and Ball, L.B., 2014, Characterization of subsurface stratigraphy along the lower American 

River floodplain using electrical resistivity: Sacramento, 

Calif., 2011: U.S. Geological Survey Open-File Report 

2014–1242, 642 p.

Helley, E.J., and Harwood, D.S., 1985, Geologic map of the 

late Cenozoic deposits of the Sacramento Valley and northern Sierran Foothills, California: U.S. Geological Survey 

Map MF-1790, scale 1:62,500, 24 p.

Lang, F.J., Jokerst, J.D., and Sutter, G.E., 1989, Habitat and 

populations of the valley elderberry longhorn beetle along 

the Sacramento River: U.S. Department of Agriculture Forest Service General Technical Report PSW-110, p. 242–248.

Merz, J.E., and Vanicek, C.D., 1996, Comparative feeding habits of juvenile salmon, steelhead, and Sacramento 

squawfish in the lower American River, California: California Fish and Game, v. 82, no. 4, p. 149–159.
Appendixes
8 Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain

Appendix 1. 

Explanation of digital data structure and content.

I. Contents

Directory: Contents:

3DFRAMEWORK Encom Discover PA project (and associated files) showing a 3-D map containing resistivity profiles, available borehole lithology and geotechnical test data, and lidar-based digital 

elevation model.

SOURCE_DATA Source databases used to compile the Encom PA projects in the 3D framework directory.

II. Geospatial Information

Horizontal Coordinate System:

California State Plane projection

Zone 2

North American Datum of 1983 (NAD83)

Units: feet

Vertical Coordinate System:

North American Vertical Datum of 1988 (NAVD88)

Units: feet

Vertical positions are referenced to the 9-feet resolution lidar-based digital elevation model provided by the U.S. Army 

Corps of Engineers Sacramento District.

III. Data Organization

Data are provided in ASCII (*.xyz) and Geosoft geodatabase (*.gdb) formats (SOURCE_DATA directory). ASCII data can 

be read with text-editing software; Geosoft geodatabases can be viewed using the Oasis montaj viewer software freely distributed by Geosoft (http://www.geosoft.com/support/downloads/viewers/oasis-montaj-viewer). 

The provided databases and grids are also presented in a 3-D framework project for the lower American River and surrounding flood plain between Cal Expo and the Rio Americano High School (3DFRAMEWORK directory). This framework 

project has been prepared using Encom PA version 12.0 and can be viewed using the PA Viewer freely distributed by Encom 

Discover PA (http://www.pitneybowes.com/pbencom/support/product-downloads.html). Symbology used in the framework project is explained in appendix 2.
Appendix 1. 9

IV. Data Information

SUBFOLDER: USGS_SECTIONDATA

DATABASE: AmRiv_USGS_DCLines.gdb

Description: Land-based direct-current (DC) resistivity section data collected by the U.S. Geological Survey (USGS) on left and 

right banks of the American River in 2007 (Asch and others, 2007) and 2011 (Burton and others, 2014).

Channel heading: Description:

CHORDLEN Chord length with respect to geospatial distance

DEM_9ft LiDAR-derived surface digital elevation model, in feet

depth_ft Depth of resistivity data point, in feet, [i]=array index

Dist_ft Along-profile distance, in feet

GPSElev_ft Orthometric NAVD88 GPS-derived surface elevation, in feet

Rho_ohmm Inverted resistivity, in ohm meters (ohm-m), [i]=array index

x_NAD83CASPz2_USft Easting, in feet

y_NAD83CASPz2_USft Northing, in feet

Year Survey year

DATABASE: AmRiv_USGS_MarineDCLines.gdb

Description: Water-borne direct-current (DC) resistivity section data collected by USGS in the American River channel in 2008 

(Ball and Teeple, 2013).

Channel heading: Description:

CHORDLEN Chord length with respect to geospatial distance

DEM_9ft lidar-derived surface digital elevation model, in feet

depth_ft Depth of resistivity data point, in feet, [i]=array index

Distance_ft Along-profile distance, in feet

H20_depth_ft Water depth derived from bathymetric echosounder, in feet

LineNum Original 2008 line number

Rho_ohmm Inverted resistivity, in ohm-m, [i]=array index

x_NAD83CASPz2_USft Easting, in feet

y_NAD83CASPz2_USft Northing, in feet

z_NAVD88_ft Water surface elevation, in feet (approximated above LiDAR with controls at river 

mile 6 and 11 using bathymetric data)

Year Survey year
10 Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain

DATABASE: AmRiv_USGS_CCLines.gdb

Description: Capacitively coupled resistivity section data collected by USGS on the left and right banks of the American River 

in 2007 (Asch and others, 2007) and 2011 (Burton and others, 2014).

Channel heading Description

CHORDLEN Chord length with respect to geospatial distance

DEM_9ft lidar-derived surface elevation, in feet

depth_ft Depth of resistivity data point, in feet, [i]=array index

Dist_ft Along-profile distance, in feet

FileName Original segment file name

Rho_ohmm Inverted resistivity, in ohm-m, [i]=array index

x_NAD83CASPz2_USft Easting, in feet

y_NAD83CASPz2_USft Northing, in feet

Year Survey year

SUBFOLDER: USACE_BORINGDATA

DATABASE: AmRivBoring_Collar.gdb, AmRivBoring_Lith.gdb, AmRivBoring_Nint.gdb

Description: Borehole lithologic and water table data provided by USACE.

Channel heading Description

DH_Hole Hole name

DH_East Easting, in feet

DH_North Northing, in feet

DH_RL Relative level referenced to lidar-derived elevations where available, in feet

DH_Dip Borehole dip angle, in degrees

DH_Azimuth Borehole-deviation direction, in degrees

DH_Top Top depth of borehole, in feet

DH_Bottom Borehole total depth, in feet

DH_From Starting depth of interval for from-to data, in feet

DH_To Bottom depth of interval for from-to data, in feet

DH_Depth Depth of point data, in feet

DEM9ft lidar-derived surface elevation, in feet

USACEElev Original elevations assigned in database

Mask Book-keeping channel

Graphic Universal Soil Classification lithologic code

Descrip Lithologic description

Length Sample interval, in feet

Recovery Recovered sample, in feet

Type Sample type

N Number of blows, corrected N1(60) used where available
Appendix 1. 11

Disclaimers

The USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released 

on condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from its authorized or 

unauthorized use. 

Although these data have been processed successfully on a computer system at the USGS, no warranty, expressed or 

implied, is made regarding the display or utility of the data on any other system, for general or scientific purposes, nor shall the 

act of distribution constitute such warranty. The USGS shall not be held liable for improper or incorrect use of the data described 

or contained herein. 

Although this information product, for the most part, is in the public domain, it may also contain copyrighted materials. 

Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the USGS or 

the U.S. Government.

V. References

Asch, T.H., Deszcz-Pan, M., Burton, B.L., and Ball, L.B., 2008, Geophysical characterization of the American River levees, 

Sacramento, California, using electromagnetic, capacitively coupled, and direct-current resistivity: U.S. Geological Survey 

Open-File Report 2008–1109, 12 p., 3 appendices, 11 plates. [Also available at http://pubs.usgs.gov/of/2008/1109/.]

Ball, L.B., and Teeple, A.P., 2013, Characterization of major lithologic units underlying the lower American River using waterborne continuous resistivity profiling, Sacramento, California, June 2008: U.S. Geological Survey Open-File Report 2013–

1050, 13 p., 5 plates. [Also available at http://pubs.usgs.gov/of/2013/1050/.]

Burton, B.L., Powers, M.H., and Ball, L.B., 2014, Characterization of subsurface stratigraphy along the lower American River 

floodplain using electrical resistivity and electromagnetics, Sacramento, California, 2011: U.S. Geological Survey Open-File 

Report 2014–1242, 42 p. [Also available at http://pubs.usgs.gov/of/2014/1242/.]
12 Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain

Appendix 2.

Lithologic description,

Universal Soil Classification System

Explanation of symbols for the lower American River geophysical framework

5,000

4,000

3,000

2,000

1,000

500

100

25

50

Resistivity (ohm-m)

N-value,

number of blows

No record

Boulder/cobble

GW

GP

GWS

GW-GMS

GW-GM

GW-GC

GW+S

GPS

GP-GMS

GP-GM

GP-GC

GMS

GM

GCS

GC

SWG

SPG

SW

SP

SW-SM

SW-SC

SP-SM

SP-SC

SMG

SM+G

SM

SCG

SC-SM

SC

MLS+G

MLS

MLG

ML+S

MHS

MH+S

ML

MH

ML-CL

CLG

CLS

CL+S

CH+S

CL-ML+S

CL-MLS

CL-ML

CL-CH

CL

CH

OL+S

OL

OH

Topsoil

Overburden

Fill

Asphalt

Concrete

No recovery

No record

Boring data Section data

Unconsolidated

sediment

Organic material

Fine Coarse

River bed detected

 during water-borne 

 resistivity profiling

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150
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For more information concerning this publication, contact:

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Federal Center, Box 25046, Mail Stop 964

Denver, CO 80025-0046

Or visit the Crustal Geophysics and Geochemistry Science Center 

Web site at: 

http://crustal.usgs.gov/
Ball and others—Digital Geospatial Presentation of Geoelectrical and Geotechnical Data for the Lower American River and Flood Plain—Data Series 902

ISSN 2327-638X (online)

http://dx.doi.org/10.3133/ds902