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Field Trip to the Oregon Coast

You know you love it.

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Atwater et al., 2005. The Orphan Tsunami of 1700—Japanese Clues to a Parent Earthquake in North America

modified from Nelson et al., 2006. Great earthquakes of variable magnitude at the Cascadia subduction zone

Location of coastal sites along the Cascadia subduction zone with evi-dence for great Cascadia earthquakes and accompanying tsunamis (after Atwater and Hemphill-Haley, 1997, their Fig. 1).

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Graehl et al., 2014. Stratigraphic and microfossil evidence for a 4500-year history of Cascadia subduction zone earthquakes and tsunamis at Yaquina River estuary, Oregon, USA

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1: low tide cliff/ramp with deposition, 2: modern shore (wave-cut/abrasion-) platform, 3: notch/inner edge, modern shoreline angle, 4: modern sea cliff, 5: old shore (wave-cut/abrasion-) platform, 6: paleo-shoreline angle, 7: paleo-sea cliff, 8: terrace cover deposits/marine deposits, colluvium, 9: alluvial fan, 10: decayed and covered sea cliff and wave-cut platform, 11: paleo-sea level I, 12: paleo-sea level II

http://commons.wikimedia.org/wiki/File%3AMarine_Terrace_diagram.png

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Map of Columbia River Basalts in the northwestern United States . Modified from Alt and Hyndman, 1985.http://geology.isu.edu/Digital_Geology_Idaho/Module10/mod10.htmAlt, D. and Hyndman, D.W., 1995, Northwest exposures, a geologic story of the northwest, Chapter 34: Floods of Ba-salt: Mountain Press Publishing Company, Missoula, MT, p. 241-248.

Volcanism in the western United States . Seligman et al., 2014http://journal.frontiersin.org/Journal/10.3389/feart.2014.00034/full

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Orr, Elizabeth L. and William N. Orr, 2012. Oregon Geology, 6th ed. Oregon State University Press.

7Orr, Elizabeth L. and William N. Orr, 2012. Oregon Geology, 6th ed. Oregon State University Press.

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Lund, E.H., 1974. ERock Units and Coastal Landforms Between Newport and Lincoln City, Oregon: Oregon Geology, v. 36, no. 5, p. 69-90.

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Igneous Rocks

Metamorphic Rocks

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Sedimentary Rocks

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Mileage Directions / Observations0 Take Lincoln Street west (turn left from campus).

0.4 Turn right on Settlemier Ave.0.6 Turn Left on OR-214 north. Drive to hwy I-5.1.7 Stay in right lane, turn right to enter I-5 onramp.1.9 Merge on I-5.

13.6 Take exit 260 A for OR-99E business (Salem Expressway) to get to HWY 22 west. Go through north Salem.

18.3 continue straight on Commercial St.18.5 Near downtown/oldtown, stay in second lane

from the right. At Marion St, turn right (onto Marion St. Bridge) to get to HWY 22 west. Stay in left lane and merge to the left to take HWY 22 west.

44.4 slight left onto the ramp to Oregon Coast44.8 Merge onto OR-18 W / OR 22 W71.8 Merge onto US-101 S73.1 Lincoln City, OR, welcome sign73.6 look left to Devil’s Lake73.8 road cut: flat lying sediments on right77.5 Morris Excavation on left: look at the tilted layers

in the cliff77.9 construction: on both sides of the road, look at

the orange and brown sediments78.7 mouth of Alsea Bay80.7 Drift Creek on right81.4 HWY 22981.8 Siletz River82.2 Ghost Forest on left83.9 Gleneden Beach86.7 Fogarty Creek: turn left, park in parking lot.

Follow trail to the north side of the creek. Turn left and head to the beach. Look at the cliffs on the right (North). Consider the stratigraphy here. There is a mudstone with fossils (the Nye Mudstone). There is a sandstone (the Astoria formation). There are nearshore/beach/dune deposits. What is at the base and what is on top?Fogarty Creek (cont.): Look to the north and to the south and note how the top of the dark bedrock is flat. Why do you think it is flat?

Fogarty Creek (cont.): walk to the south to-wards the big dark rocks that are sticking up out of the sand. Take a look at the rocks. Do they look like any of the rocks you already looked at? What kind of rocks do you think these are?

86.9 Head back to HWY 101, turn left (South)87.9 Boiler Bay Marine Terraces to the North88.3 Depoe Bay: keep your eyes peeled for the bed-

rock on the right89.3 try to park on the right (before the bridge), look

at the marine terraces91.1 View to the right, Whale Cove91.3 Rocky Creek93.1 Cape Foulweather94.2 Devil’s Punchbowl, turn right94.3 turn left on Otter Crest loop94.4 go forward94.5 turn right at Devil’s Punchbowl State Park sign95 park in parking lot on right, go back to road and

turn right towards the coast (West). At end of road is the Devil’s Punchbowl. Take a look at the stratigraphy. What do you see?

Walk to the north and take a look at the rock outcrops to the North. Describe what you see. Have you seen this before?

Walk to the South, follow the trail as it curves to the left. Stop where you can see a good view of the cliff below. Describe the stratigraphy.Get back in your vehicle, take the road back East bound.

95.6 turn right at stop sign96 Get back on HWY 101 (forward)97 Beverly Creek

99.4 Yaquina Head on right (stay on HWY 101)102.7 turn right on NW 11th St.103.3 turn left on NW Spring St and park on right.

Return to NW 11th St. on foot, turn left (West) and head to dead end. This is the Jumpoff Joe stop. Walk out onto the concrete platform (an old house foundation). Walk to the right (North). Look at the trees that are on the ground surface below. How do you think they got there? Is this related to why the house was abandoned.Walk to the south of the concrete platform and look at the cliffs to the South. What do you see here?

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103.3 Go back to the vehicle and head south on Spring St.

103.5 Turn right, follow the yellow line103.5 Turn left on NW Coast St103.8 Stop Sign at Nye Beach, stay on Coast St.103.9 Turn Right on W Olive St.104 Davis Beach Park (optional stop). Follow road

curve, road changes name to SW Elizabeth St.104.8 Turn Right on SW Government St.

Follow road curve and park on right near the Yaquina Bay Lighthouse.Walk to the overlook (with the four signs). On your left is the bridge. Near sea level, below you, there is a flat horizontal surface. What is this? How was it formed?Get back in your vehicle, take the road back East bound.

105.2 Turn left at Stop Sign

Turn Right and Stop Sign, then right again to get on HWY 101 and to head southbound over bridge

105.9 Turn Right at “OR Coast Aquarium / OSU Hatfield Marine Science Center” Sign

106.3 Under bridge106.4 Turn Right at Stop SIgn106.5 Pass OR Aquarium (on left)106.8 Go forward through Stop Sign107 Turn Left at Idaho Point

107.1 Dead End Sign108.2 Turn around and go back on same road108.6 Park on the right. Go down to the sand flats.

This is one of the coring locations from various studies that looked for evidence of coseismic subsidence and tsunami inundation.

108.6 return to vehicle and head West towards coast.109.3 Turn Left at Ferry Slip109.4 Turn left on HWY 101 southbound117 Ona Beach State Park (stay on HWY 101)

118.5 Turn Right at Seal Rock State Wayside. Park and take trail from southern end of parking lot. Follow trail to the beach. “Elephant Rock” is the large cliff to the west. This is a sill that formed between sedimentary layers. Describe what you see.

Walk to the base of Elephant Rock and look at the sedimentary bedding. Note the contact between the underlying lighter colored rock and the overlying dark rock. What type of rocks are these? Describe the contact between these two rocks.Walk back to the base of the cliff. Note there are two types of sediment on the beach. One is dark and one is light. Where did these sedi-ments come from?Get back in your vehicle and return to HWY 101

124.3 Driftwood Beach126.4 Alsea Bridge127 Turn Right at Stop Light

127.3 Park in parking lot. Walk to West, towards the coast. Take a look across the river mouth to the sand spit.Get back in vehicle and head back west on road you drove in on.

127.4 Turn left at Stop Light, heading back northbound on HWY 101.Drive back to Newport.

143.3 Turn Right and head eastbound on HWY 20.164.8 If possible, pull over on right and park at the

side of the road. Look at the road cut. There are some sedimentary layers that are part of the Tyee formation. Describe these rocks. What type of rocks are these?Return to the vehicle and continue eastbound on HWY 20.

195.4 Turn Right at Stop Light, heading eastbound on HWY 20/34 towards the interstate HWY I-5

205.1 Enter I-5 northbound and return to CCC Wood-burn Campus

248.9 Exit HWY I-5, head east to return to CCC Wood-burn Campus

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http://tidesandcurrents.noaa.gov/noaatidepredictions/viewDailyPredictions.jsp?bmon=05&bday=17&b-year=2015&timelength=daily&timeZone=2&dataUnits=0&datum=MLLW&timeUnits=2&interval=highlow&-Threshold=greaterthanequal&thresholdvalue=&format=Submit&Stationid=9434939

WALDPORT, OR StationId: 9434939Daily Tide Prediction in MetersTime Zone: LST/LDTDatum: MLLW

Jackson, P.L. and Rosenfield, C.L., 1987. Erosional changes at Alsea Spit, Waldport, Oregon: Oregon Geology, v. 49, no. 5, p. 55-59.