Oregon Geology - Oregon Geology -

Parent of the Soil, Parent of the Soil,

Foundation for the Vine Foundation for the Vine

By Ray Wells ay Wells1

Open File Report 2006-1069

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

U.S. Government.

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

1Menlo Park, Calif.
Oregon Geology - Oregon Geology -

Parent of the Soil, Parent of the Soil,

Foundation for the Vine Foundation for the Vine

Ray Wells

US Geological Survey, 345 Middlefield Rd. MS 973, Menlo Park, CA, 94025

Project Chief, Pacific Northwest Urban Corridor Geologic Mapping

Project Website: http://geology.wr.usgs.gov/wgmt/pacnw

Cooperators - Alan Campbell, Cooperators - Alan Campbell, Chemeketa hemeketa Community College, Salem, Oregon ommunity College, Salem, Oregon

Dave Johnson, Natural Resources Conservation Service, Salem, Oregon Dave Johnson, Natural Resources Conservation Service, Salem, Oregon
Here we are on the leading edge Here we are on the leading edge....

 This is where the Juan de Fuca oceanic plate dives beneath North America and

sinks into the earth’s deep mantle.

 This zone of convergence is called the Cascadia subduction zone, and it is the

source of our rocks, geologic hazards, and landscape.
Outline of Talk

 Rationale for USGS Geologic Mapping in

Oregon

 Geologic map products

 Thumbnail sketch of geologic history

 New mapping in progress - NW Oregon

 Tour of NW Oregon geologic units

 Online sources of information
Subduction Subduction

creates creates

earthquakes earthquakes

and volcanoes and volcanoes

Earthquakes:

Green = N. Am plate

Red = J. de Fuca plate

Triangles=major volcanoes

Urban Corridor is Urban Corridor is

seismically active seismically active

and is an area of and is an area of

intense study by intense study by

USGS.

Portland Portland

Seattle Seattle
 Earthquakes Earthquakes

are created by are created by

motions of motions of

crustal blocks crustal blocks

 Small plates and blocks Small plates and blocks

are dragged northward by are dragged northward by

Pacific Plate Pacific Plate

 Blocks collide with one Blocks collide with one

another - a terrane wreck another - a terrane wreck

- as they encounter the - as they encounter the

fixed buttress of Canada. fixed buttress of Canada.

(from Wang et al., 2003, modified from Wells et al., (from Wang et al., 2003, modified from Wells et al.,

1998, Wells and Simpson, 2001; see also Magill et al., 1998, Wells and Simpson, 2001; see also Magill et al.,

1982; Walcott, 1993; Pezzopane and Weldon, 1993; 1982; Walcott, 1993; Pezzopane and Weldon, 1993;

Argus and Gordon, 1991) Argus and Gordon, 1991)
Geologic mapping is Geologic mapping is

focused on convergent focused on convergent

margin and I-5 Urban margin and I-5 Urban

Corridor. Corridor.

 Provide information useful Provide information useful

for geologic hazard and for geologic hazard and

resource assessments. resource assessments.

 Distribution, age, and Distribution, age, and

composition of geologic composition of geologic

units (rocks and units (rocks and

sediments) sediments)

 Geometry and age of Geometry and age of

geologic structure (folds geologic structure (folds

and faults) and faults)
100 K Geologic 100 K Geologic

Mapping Mapping

 Scale - 1:100,000 (1

inch on map = 1.6 miles

on ground)

 On the web as PDFs and

ArcGIS files

 State of Washington has

complete digital

geologic coverage at

this scale (WADNR)

 State of Oregon in

progress
Geologic Map of Roseburg 100,000-scale quad Geologic Map of Roseburg 100,000-scale quad

 Online at http://geopubs.wr.usgs.gov/open-file/of00-376/ Online at http://geopubs.wr.usgs.gov/open-file/of00-376/
7.5’ quad geology quad geology

 More detail - Scale is More detail - Scale is

1:24,000 (1 inch on map 1:24,000 (1 inch on map

= 0.38 miles on ground) = 0.38 miles on ground)

 I-5 Urban Corridor I-5 Urban Corridor

 On line as PDFs and On line as PDFs and

ArcGIS geodatabases ArcGIS geodatabases

 OR and WA state OR and WA state

surveys (DOGAMI and surveys (DOGAMI and

WADNR) also publish WADNR) also publish

similar maps similar maps
 139 7.5 139 7.5’ quads published or quads published or

in progress by USGS, in progress by USGS,

DOGAMI, WADGER, DOGAMI, WADGER,

OSU, and PSU along I-5 OSU, and PSU along I-5

corridor and major fault corridor and major fault

zones

 All will be digital and All will be digital and

available online available online

Status of 7.5 Status of 7.5’

mapping Portland- mapping PortlandSalem area Salem area
Online 7.5 Online 7.5’ map Deer island, OR-WA map Deer island, OR-WA

Evarts and others, 2002; http://pubs.usgs.gov/mf/2002/2392/ Evarts and others, 2002; http://pubs.usgs.gov/mf/2002/2392/
Distribution of geologic maps online:

http://geology.wr.usgs.gov/

wgmt/pacnw
Cascadia Cascadia

Physiography Physiography

Subduction of Juan de Subduction of Juan de

Fuca plate: Fuca plate:

 Holds up Coast Range Holds up Coast Range

(1)

 Depresses Puget- Depresses PugetWillamette trough (2) Willamette trough (2)

 Builds active Cascade Builds active Cascade

volcanic arc (triangles) volcanic arc (triangles)

Convergence

velocity

mm/yr

1

2
Cascadia Cascadia’s geologic history - A thumbnail geologic history - A thumbnail

sketch of 6 big events: sketch of 6 big events:

 For example - Imagine the Hawaiian Islands rafting into the

subduction zone...
1. Collision of ocean island chain with 1. Collision of ocean island chain with

continent continent

 Island chain - similar to Island chain - similar to

Hawaiian Islands - crashed into Hawaiian Islands - crashed into

N. America and was accreted to N. America and was accreted to

the continent at about 50 Ma the continent at about 50 Ma

(million years ago). (million years ago).

50 Ma (million years ago)

52 million-year-old submarine 52 million-year-old submarine

pillow basalt, Trask River pillow basalt, Trask River

Roseburg Quad Roseburg Quad
 Subduction zone jumped Subduction zone jumped

westward. Sand and mud from westward. Sand and mud from

rivers built offshore deltas, rivers built offshore deltas,

shoreline deposits and shoreline deposits and

submarine fans. submarine fans.

2. Marine sediments were deposited on the 2. Marine sediments were deposited on the

accreted terrane in W. Oregon and accreted terrane in W. Oregon and

Washington Washington

50-15 Ma

Cowlitz sandstone 40 Ma
 Volcanic activity

continues to the present.

3. Cascade arc volcanoes buried the eastern 3. Cascade arc volcanoes buried the eastern

edge of the marine sediments and the edge of the marine sediments and the

accreted terrane. accreted terrane.

40-0 Ma

Mount St. Helens Nov 05
4. Crustal stretching released a flood of basalt 4. Crustal stretching released a flood of basalt

from fissures east of the arc from fissures east of the arc

 Columbia River Basalt Columbia River Basalt

(CRB)

 80% by volume erupted 80% by volume erupted

between 16.2 and 15.5 Ma between 16.2 and 15.5 Ma

 Flowed 450 mi. into Flowed 450 mi. into

Pacific Ocean Pacific Ocean

17-6 Ma

CRB, Ginkgo State

Park, WA.
The resulting rock sequence in NW Oregon:

History Age

 Modern rivers 15-0 Ka

 Glacial outburst 15 Ka

floods (Missoula flood)

 Columbia R. Basalt 15 Ma

 Deposition of 40-20 Ma

shallow-water

marine sediments

 Deposition of 50-45 Ma

deep marine sediments

basalt intrusion

 Accretion of oceanic 50 Ma

basalt terrane to

N. America “Siletzia”

Rock type

 Mud and sand

 Silt and sand

 Basalt lava flows

 Fine grained sandstone

 Sandstone

 siltstone

 Basalt intrusions

 Basalt flows (submarine

pillow basalt)
5a. An eastward 5a. An eastward “push” from Juan de Fuca from Juan de Fuca

plate causes uplift of the Coast Range. plate causes uplift of the Coast Range.

 Uplift

View S. toward Cape Lookout, OR.

12-0 Ma
5b. The strata in the uplifted Coast Range

were folded into a broad arch, with the oldest

rocks in the center.

50-million year-old Siletz River Volcanics 50-million year-old Siletz River Volcanics

15-million year-old Columbia River Basalt 15-million year-old Columbia River Basalt

40-million year-old diabase (basalt) intrusions 40-million year-old diabase (basalt) intrusions

30-million year-old marine sandstone and mudstone 30-million year-old marine sandstone and mudstone
 26 Rhythmically-bedded 26 Rhythmically-bedded

Missoula flood silts; Missoula flood silts;

Highway 26 at Cornell Rd. Highway 26 at Cornell Rd.

6. Catastrophic glacial outburst

floods (at least 40) filled the

Willamette Basin, leaving a

blanket of silt on everything

below ~ 400’ elevation.

18-15 ka (thousand yrs ago)

http://geopubs.wr.usgs.gov/open-file/of03-408/
Oregon Geologic Map Oregon Geologic Map  Areas of new USGS Areas of new USGS

mapping in purple mapping in purple

 American Viticultural American Viticultural

Areas (AVAs) in blue Areas (AVAs) in blue

Coast Range arch

 Area of detail in next slide

Geology Geology

simplified from simplified from

Walker and Walker and

Macleod, 1991 Macleod, 1991


Line of cross section
Mountains are held up by basalt.

Sandstone and siltstone underlie lower ridges

and valleys.

SW NE

Idealized cross section Idealized cross section

Geologic

 formation

 names

Rock type
 Marine sedimentary Marine sedimentary

rocks (yellow and rocks (yellow and

green)

 Spencer sandstone Spencer sandstone

 Yamhill siltstone Yamhill siltstone

 Keasey Formation Keasey Formation

 Pittsburg Bluff Pittsburg Bluff

Fm.

 Basalt intrusions Basalt intrusions

(purple and red) (purple and red)

Yamhill-Carlton Yamhill-Carlton

AVA
Diabase (coarse-grained basalt intrusion)

holds up many hills in Yamhill-CarltonMcMinnville area
Yamhill-Carlton Yamhill-Carlton

 Spencer

Formation

sandstone

 Underlies

“Willakenzie

Ridge”

Well-exposed Spencer Formation sandstone at Hagg Lake Well-exposed Spencer Formation sandstone at Hagg Lake
Ribbon Ridge Ribbon Ridge

AVA

 Pittsburg Bluff

Formation

 Marine fine Marine fine

sandstone, siltstone, sandstone, siltstone,

and mudstone and mudstone

 Volcanic tuff beds Volcanic tuff beds

from Cascade arc from Cascade arc
Ribbon Ridge Ribbon Ridge

 Loess

(windblown

silt)

 Paleosol

(orange)

 Sandstone of

Pittsburg

Bluff
Chehalem Chehalem

Mountains Mountains

AVA

 Columbia River Columbia River

Basalt

 Loess cap Loess cap

 Slide bench of Slide bench of

basalt on SW side basalt on SW side

 Pittsburg Bluff Pittsburg Bluff

marine

sedimentary rock sedimentary rock

down low on down low on

west side. west side.
Flow by flow stratigraphy of the CRB Flow by flow stratigraphy of the CRB

 Individual flows of

CRB can be recognized

with chemistry, physical

appearance, and

paleomagnetism.
Chehalem Mountains

 Columbia River Basalt (CRB) Columbia River Basalt (CRB)

 Sentinel Bluffs Mbr. of Grande

Ronde Basalt

 Loess (wind-blown silt) over Loess (wind-blown silt) over

Jory-like paleosol on CRB Jory-like paleosol on CRB
Dundee Hills AVA

 Mostly Columbia Mostly Columbia

River Basalt River Basalt

 Frenchman Springs

Member

 Grande RondeSentinel Bluffs Mbr

 Grande RondeWinter Water/Ortley/

Wapshilla flows

 Landslide bench on

N and W
Dundee Hills Dundee Hills

 Columbia River

Basalt beneath

Jory Soil

 Grande Ronde Grande Ronde

Basalt in Basalt in

distance distance

 Frenchman Frenchman

Spr. Mbr. Of Spr. Mbr. Of

Wanapum Wanapum

Basalt in upper Basalt in upper

part of part of

vineyard vineyard

Maresh Vineyard
What is the take away? What is the take away?

 From the Rogue to the Tualatin, each hillside

has a story.

 Geology provides the landscape, its

interaction with the sun and water, and the

parent materials for the soils...

 And it holds up the vineyards!