Activities with the Virtual Environment

 

Coplias River, Washington

 

Activity - Moving beach sediment

Go to Copalis River Viewpoint 1. Turn slowly around slowly a complete 360°.

Copalis River, Washington, Viewpoint 1 – Copalis Beach
47.06.68’ / 123°10.94’W / Elevation 1 m (3.3 ft)

Background:
       In this scene, you are looking at the beach to the west of the Copalis River in western Washington.  If you look due east (azimuth 090°), you see the town of Copalis Beach.  The Copalis River flows through the town about half a kilometer from this viewpoint.  Though most of the sediment in the river is mud (very fine sediment), you can find thin layers of sand in the banks surrounding the river several kilometers upstream.

Questions:

  • Do you see any other kind of sediment besides sand in this scene? 
  • Turn around to azimuth 260°.   What does the beach look like in this direction?  Now turn to azimuth 355° and answer this same question.  Suggestion – To help answer this question move your cursor over the “Enhance button" at the bottom of the frame.
  • Based on what you saw at azimuth 260° and 355°, what are some ways that sand is being moved from place to place on this beach?
  • Do you think any of these ways are capable of transporting sand several kilometers inland?
  • If not, what are some other ways that sand might be transported that far from this place?

 

 

Activity - Dating a tree stump

Go to Copalis River Viewpoint 2. Turn to 315° and click on the green plus sign that appears to get a closer look at the stump.

Copalis River, Washington, Viewpoint 2
47.06.90’ / 123°10.46’W / Elevation 1 m (3.3 ft)

Background:
       In this scene, you are looking at a tree stump that may have been washed ashore by a flood on the Copalis River.  When you zoom in on the stump, you can see a cross section of the tree where it has been cut.  If you count the rings beginning at the center of the tree, you can determine how old it was when it died.  This same strategy is one of the techniques used to determine when the last subduction zone earthquake occurred in this area.          

Questions

  • How old was this tree when it died?
  • Why do you think some of the tree rings are thicker than others?
  • Using your answer from the previous question, how could you compare the rings of this tree to a tree from the same area that died more recently?

 

 

Activity - Investigating a ghost forest

Go to Copalis River Viewpoint 3. Turn to 085° and click on the green plus sign that appears to get a close look at the tree stump.

Copalis River, Washington, Viewpoint 3
47.07.64’ / 123°09.74’W / Elevation 2 m (6.6 ft)

Background:
       In this scene, you are looking at a tree that was killed when an earthquake and a tsunami struck the coast of Oregon, Washington, and British Columbia in 1700 AD.  Geologists have studied this tree seeking to better understand the last major tsunami to hit this area.

Questions:

  • What do you think happened to this tree since it died about 300 years ago?  To answer this question move up and down the tree looking for damage you think occurred after the tree died?
  • Move down to the bottom of the tree and click on the green plus sign to magnify the tree.  This is a place where researchers have been studying the tree.  What have they done to the tree?  What do you think they were looking for when they did it?  Hint – Think about what you may have seen at Copalis River Viewpoint 2.
  • Near the bottom of the tree you might notice that researchers dug down about a meter to find the original forest floor.  How could this forest floor have gotten buried?
  • Are there any other viewpoints on the Copalis River where you can see buried forest floor or marsh?

 

 

Activity - Examining a muddy stream bank

Go to Copalis River Viewpoint 5. Turn to 315° and click on the green plus sign that appears on the bank.

Copalis River Viewpoint 5
47.07.45’ / 124°09.74’W / Elevation 0 m (0 ft)

Background:
       In this scene you are looking at a muddy stream bank on the edge of the Copalis River.  The bank has been scraped with a shovel to expose layers of mud, sand, and peat.   

Questions

  • Going from top to bottom list the layers of sediment that are exposed in the bank.  To do this, make a drawing of the bank and label each layer.
  • How thick is each layer?  Mark this on your drawing.
  • Which layer contains sediment that is being deposited in this place now?
  • Which layer contains sediment that definitely came from some place else?  How do you think this sediment got here?

 

Niawiakum River, Washington

 

Activity – People and the last subduction zone earthquake

Go to Niawiakum River Viewpoint 3. Turn to 010° and click on the green plus sign that appears to get a closer look at the bank on the other side of the river.

Niawiakum River Viewpoint 3
46°37.73’N / 123°54.63’W / Elevation 2 m (6.6 ft)

Background:
       In this scene you are looking at a bank of the Niawiakum River near its mouth.   Exposed in the bank are layers of sediment and other materials that have accumulated over several hundred years.      

Questions:

  • Going from top to bottom, list the layers that are exposed in the bank.  To do this, make a drawing of the bank and label each layer.
  • What is in each layer and how thick is it?  Mark this on your drawing.
  • Which of the layers may have been created by people?  How was it created?
  • Why is this layer now buried?

 

 

Activity - Examining a muddy stream bank

Go to Copalis River Viewpoint 4. Turn to 035° and click on the green plus sign that appears to get a closer look at the stream bank.

Niawiakum River Viewpoint 4
46°37.86’N / 123°55.28’W / Elevation 0 m (0 ft)

Background:
       In this scene, you are looking at a muddy stream bank on the shore of the Niawiakum River.  The bank has been scraped with a shovel to expose layers of mud, sand, and peat.   

Questions

  • Going from top to bottom list the layers of sediment that are exposed in the bank.  To do this, make a drawing of the bank and label each layer.
  • How thick is each layer?  Mark this on your drawing.
  • Which layer probably used to be marshland?
  • Which layer did the river probably deposit?
  • Which layer contains sediment that came from someplace else?
  • Where do you think this sediment came from, and how did it get here?  Hint – Zoom back to the aerial view of the southwestern Washington Coast.

 

 

Activity – Fieldwork on a muddy stream bank

Go to Niawiakum River Viewpoint 5 and turn to azimuth 125°.

Niawiakum River Viewpoint 5
46°37.87’N / 123°55.28’W / Elevation 0 m (0 ft)

Background:
       In this scene, you are looking at a muddy stream bank on the shore of the Niawiakum River.  The person on the right is Brian Atwater of the US Geological Survey.  Dr. Atwater is a geologist who has been researching the history of great earthquakes and major tsunamis in the Pacific Northwest.  Here he is scraping away the outer layers of a bank of the Niawiakum River using a shovel. 

Questions

  • Dr. Atwater is working his way from left to right.  How does the bank on his right compare to the bank on his left?
  • What information does scraping away the outer surface of the bank reveal?
  • Turn to azimuth 100° and sketch the bank.  Why do you think the bank has layers in it?

 

 

Activity - Forest and marshland on tidal river

Go to Niawiakum River Viewpoint 6.  Slowly turn completely around.

Niawiakum River Viewpoint 6
l46°37.88’N / 123°54.27’W / Elevation 2 m (6.6 ft)

Background:
       In this scene, you are looking at the lower reach of the Niawiakum River just upstream from where it empties into Willapa Bay in southwestern Washington.  Since we are so close to a saltwater bay, the river is a mixture of salt and freshwater that rises and falls with daily tides.  Adjacent to the channels are broad grasslands called tidal marshes.  Farther back are forests.  During low tide that channel is surrounded by flat muddy areas called mudflats or tidal flats.

Questions:

  • Since the Niawiakum River is a freshwater stream flowing into a saltwater bay, what do you think happens to the salinity (salt content) of the water as you move further upstream?
  • Further upstream, the forest grows right next to the river.  But here, only grasses grow next to the water and you have to walk a hundred meters or more to get to the forest.  You are also going uphill a few meters.  Why do you think the trees don’t grow next to the river?
  • In places like the Copalis River you find ghost forests, which are groups of trees that died suddenly at the same time.  Based on your answer to the last question how could this have happened?

 

Seaside, Oregon

 

Activity - Tsunami Flooding

Go to Seaside Viewpoint 1 and turn around to azimuth 105° 

Seaside Viewpoint 1
46°00.42’N / 123°55.08’W / Elevation 1 m (3.3 ft)

Background:
This scene is barely a meter (3.3 ft) above sea level.  The building in the center of your view is part of Seaside High School.

Questions:

  • How high did the water rise in the 1964 tsunami?  How high did it rise during the 1700 tsunami? To address this question, look for the high water marks that appear on the utility pole when you select “Enhance” from the “Toolbox” that appears at the bottom of the screen.  Select the “Measure” option to determine the elevation of each mark.
  • In the event of a tsunami like the one in 1964 where in the school building could you go to get above the water?  Be specific.
  • In the event of a tsunami like the one in 1700 is there anywhere you could go to get above the floodwaters?

 

 

Activity –Tsunami Evacuation

Move to Seaside Viewpoint 1 and turn around to azimuth 105° 

Seaside Viewpoint 1
46°00.42’N / 123°55.08’W / Elevation 1 m (3.3 ft)

Background:
This scene is barely a meter (3.3 ft) above sea level.  The building in the center of your view is part of Seaside High School.  While the high school is largely made of brick, many of the other buildings that you see from this place are made of wood.  The ground on which these buildings are built is largely filled in marshland or dune fields (part of a sandy beach). 

Questions:

  • There is strong evidence that Oregon and Washington experience strong earthquakes (magnitude 8.0 and larger) on the average of once every 300 years.   If such an earthquake were to happen today, how would the buildings you see be damaged?  What others kinds of damage might you expect?  Be specific by giving the azimuth of four or five features (roads, buildings, utility poles, etc.), describe their construction (what they are made of and how), and explain what kind of damage might occur to them. 
  • A large earthquake like the one in the previous questions can produce a tsunami reaching heights of 10 m (33 ft).  In many Oregon and Washington coastal towns this means walking, not driving to higher ground.  Based on what you said for the previous question, why are citizens instructed to walk rather than drive to safety?
  • This place is the beginning of one of Seaside’s evacuation routes.  The safe assembly point for Evacuation Route #2 is 2 km (1.3 mi) away.  The route is all on paved road and is fairly flat.  How long does it take you to walk this far?  To answer this question, go outside and time yourself as you walk this distance.
  • In the event of a major earthquake off the Oregon Coast it is estimated that you would have 20 minutes after the earthquake to reach high ground.  Based on the time it took you to walk 2 km, would you have enough time to make it from this viewpoint to safety?

 

Young's Bay, Oregon

 

Activity - Exploring the banks of the Lewis and Clark River

Go to Youngs Bay Viewpoint 3. Turn to azimuth 050° and click on the green plus sign that appears on the bank.

Young’s Bay Viewpoint 3
46°09.34’N / 123°51.36’W / Elevation 0 m (0 ft)

       In this scene you are looking at a muddy stream bank on the edge of the Lewis and Clark River near Astoria Oregon.  The bank has been scraped with a shovel to expose layers of mud, sand, and peat.   

Questions

  • Going from top to bottom list the layers of sediment that are exposed in the bank.  To do this, make a drawing of the bank and label each layer.
  • How thick is each layer?  Mark this on your drawing.
  • Which layer contains sediment that is being deposited in this place now?
  • Which layer contains sediment that definitely came from some place else?  How do you think this sediment got here?

 

 

Activity - Trees in the Mud

Go to Youngs Bay Viewpoint 9. Slowly turn completely around. 

Young’s Bay Viewpoint 9
46°09.44’N / 123°51.30’W / Elevation 0 m (0 ft)

Background:
       In this scene you are looking at the shore of Young’s Bay during an extreme low tide.  Here you are standing on a gently sloping surface called a mudflat.  When you dig down into the flat, you find thick layers of clay-rich mud. In addition to mud, you find a large number of logs on the flat. 
      If you are curious about what this area looks like during high tide go back to Viewpoints 5 and 6.   

Questions:

  • Where are the logs on the mudflat?  Give a direction and a distance from the shore.
  • Where do you think the logs came from?  How did they get there? 
  • What local evidence do you have for your answer to the last question?  To find local evidence go back and look at the other viewpoints in this area.

 

Mt. Hood, Oregon - White River Canyon

 

Activity - Stream flow and sediments

Go to Mt. Hood White River Canyon Viewpoint 7.  Slowly turn right from azimuth 315° to 110°.

White River Canyon Viewpoint 7
45°18.41’N / 121°40.63’W / Elevation 1336 m (4382 ft)

Background:
       The river in this scene, White River, is one of the major rivers flowing off the slopes of Mt. Hood. 

Questions:

  • How would you describe the flow of White River? For example is it moving quickly or slowly?  Is the flow turbulent or smooth?
  • How would you describe the river channel?  For example is it deep or shallow?  Is it a single channel or several channels?
  • Turn to azimuth 330°.  How does the sediment in the stream compare with the sediment on the stream bank?
  • Could the stream, flowing like it is now, have carried and deposited the sediments on the stream bank?
  • If not, how did these sediments get to where they are on the stream bank?

 

Mt. Hood, Oregon - Eliot Glacier

 

Activity - Failing slopes

Go to Mt. Hood Eliot Glacier Viewpoint 2 and turn to azimuth 240°.

Eliot Glacier Viewpoint 2
45°23.94’N / 121°39.46’W / Elevation 1870 m (6133 ft)

Background:
       The ridge you are looking at in this scene is called a lateral moraine.  It is a chaotic pile of boulders, gravel, and sand that is deposited along of the side of the glacier. 

Questions:

  • What has happened to moraine at this place?  To help you answer this question move right and left to look and the rest of the moraine and compare this part of the ridge to other parts.  You can also move the cursor over the “Enhance” button as you do so to get additional information about the slope.
  • Why has this happened right here?
  • What happened to this slope occurred during a particularly wet winter and created a debris flow traveled several kilometers downstream.  How could this event have produced a debris flow?

 

Mt. Hood, Oregon - Heather Canyon

 

Activity – Examining the Rocks

Go to Mt. Hood – Heather Canyon Viewpoint 1 and turn to azimuth 300°. Click on one the green plus signs on the ground to look more closely at it.

Heather Canyon Viewpoint 1
45°20.88’N / 121°40.28’W / Elevation 2056 m (6744 ft)

Background:
       Like many volcanoes in the Cascades, Mt. Hood is largely made up of a rock called andesite.  Click on the green plus signs to look closely at a couple of samples of this rock.  Both rock samples are crystalline, meaning that they are composed of interlocking crystals.  Since andesite is a volcanic rock, these crystals formed when magma (molten rock) cooled.  In general, the more slowly magma cools, the larger the crystals are when it solidifies.

Questions:

  • How are the samples different?
  • How are they the same?
  • Looking at the sample of red andesite, what do you notice about the crystals that make up the rock?
  • Based on crystal size, would you say about how this rock cooled?  Was cooling slow or quick?  Did it cool all at once or in stages?

 

 

Activity – Examining a lava flow

Go to Mt. Hood – Heather Canyon Viewpoint 1 and turn to azimuth 055°.  Click on one the green plus sign on the ridge to look more closely at it.

Heather Canyon Viewpoint 1
45°20.88’N / 121°40.28’W / Elevation 2056 m (6744 ft)

Background:
       This ridge, Gnarl Ridge, is the eroded remains of a lava flow produced by one or more past eruptions of Mt. Hood.  The flow most likely traveled down an old stream or glacial valley that has since been eroded away. If you look closely at the ridge, you see sets of vertical columns that were produced as the lava cooled.

Questions:

  • Where do you see the columns?  How many rows of columns do you see?   To answer these questions, make a sketch of the ridge and mark on it where each row is.
  • Do you think this is one, two, or more lava flows?  If you think it is more than one lava flow, mark on your sketch where you think the boundaries between the flows are.
  • If you could go to Gnarl Ridge, what would you look for to test the hypothesis you made when you answered the previous question?

 

Hood River Valley, Oregon

 

Activity - Debris flows in the Hood River Valley

Go to Hood River Valley Viewpoint 2 and turn to azimuth 115°.

Rail line (Hood River Valley, Oregon)
45°40.71’N / 121°30.58’W / Elevation 105 m (344 ft)

Background:
       This rail line runs from Hood River to Parkdale, Oregon through the Hood River Valley.  This valley is one of the richest agricultural areas in the state of Oregon and world famous for its orchards.  It is also the site of numerous debris flows produced by rainy winter weather and volcanic eruptions.  The sediments exposed in this outcrop were deposited by a debris flow that occurred during a prehistoric eruption of Mt. Hood.

Questions:

  • How would you describe the sediments in this outcrop?  What color are they?  What shape are they?  How big are they?  Are they uniform (all the same size and color) or is there a mixture?
  • Based on the assumption that they were deposited by Hood River, what would you say about how fast and how deep the water was flowing when they were deposited?
  • Why did you answer what you answered in the last question?
  • How would you test your answer?

 

Mt. Rainier, Washington - Nisqually River Watershed

 

Activity – Ricksecker Point Outcrop

Turn around to azimuth 020° and click on the green plus sign on the outcrop to look more closely at it.

Mt. Rainier National Park - Ricksecker Point Viewpoint 1
46°46.11'N / 121°46.39' W / Elevation 1295 m (4249 ft)

Background:
The rock and sediment in this outcrop comes from three sources.  

  1.   A lahar from Mt. Rainier 5600 years ago.
  2.   Volcanic eruptions of Mt. St. Helens (1479 AD) and Mt. Mazama (Crater Lake) 7600 years ago.
  3.   Glaciers covering Mt. Rainier during the last major ice age 15,000 to 22,000 years ago. 

Questions:

  • Where are the boundaries between each deposit?
  • How does the material in each layer compare?

Suggestion - Draw and label a picture of the outcrop to answer these questions.

 

 

Activity – Flood marker

Move to Mt. Rainier National Park – Tahoma Creek Viewpoint 5 and turn to azimuth 215°.  Click on the green plus sign on the stump to look at it more closely.

Mt. Rainier National Park - Tahoma Creek Viewpoint 5
46°47.49'N / 121°53.91' W / Elevation 960 m (3150 ft)

Background:
      Winter floods in 2006 damaged the stump in this scene and created much of the destruction that you see in this scene.

Questions:

  • How is the stump damaged?
  • How do you think the flood caused this damage?
  • What does the damage tell you about which way the flood went?

 

 

Activity – The flow of Tahoma Creek

Move to Mt. Rainier National Park – Tahoma Creek Viewpoint 6 and turn to azimuth 055°.  Click on the green plus sign on the stump to watch the normal flow of Tahoma Creek during the summer.

Mt. Rainier National Park - Tahoma Creek Viewpoint 6
46°47.47'N / 121°52.89' W / Elevation 955 m (3133 ft)

Background:
      Tahoma Creek is a tributary of the Nisqually River.  During summer the creek is fed by melting snow and ice high on the southwest slopes of Mt. Rainier.  During the summer the flow of stream looks much like you see in this movie.  At unusual times the creek will be much larger and run much more rapidly, filling the valley floor with a rushing mass of water, mud, rock, and trees called a debris flow.  Debris flows may result from volcanic eruptions, winter storms, or glacial outbursts (when large volumes of water suddenly and unexpectedly burst out from under a glacier).

Questions:

  • What does the summer flow look like?
  • What type of sediment (boulders, gravel, sand, and mud) seems to be carried by the stream?
  • Looking at the area around the creek, which sediments do you think were brought there by normal stream flow?  Which do you think were brought there by debris flows?

 

Electron, Washington

 

Activity - Outcrop of Electron Mudflow Deposits

Move to Electron, Washington Viewpoint 1 and turn around to azimuth 090°.  Click on the green plus sign that appears to look more closely at the outcrop.

Electron Washington Viewpoint 1
46°59.77'N / 122°11.55' W / Elevation 185 m (607 ft)

Background:
       The sediment you see in this scene was deposited by a debris flow from Mt. Rainier that happened approximately 1200 years ago.  A debris flow is a rapidly moving flow of mud, rock, trees, and water.  A steam explosion on the southwestern slope of Mt. Rainier probably triggered a massive landslide, causing this particular debris flow. 

Questions:

  • Where does the soil stop and the mudflow begin?
  • How did you decide where the boundary was?
  • What other material, besides mud did the flow deposit?

Suggestion - Draw and label a picture of the outcrop to answer these questions.

 

Mud Mountain Dam, Washington

 

Activity – Interpreting mudflow deposits I

Move to Mud Mountain Dam, Washington Viewpoint 3 and turn around to azimuth 310°.  Click on the green plus sign that appears to look more closely at this outcrop.

Mud Mountain Dam, Washington Viewpoint 3
47°09.38'N / 121°54.17' W / Elevation 335 m (1165 ft)

Background:
This sediment was deposited by a mudflow from Mt. Rainier that happened approximately 5600 years ago.  This mudflow was considerably larger than the one that deposited the sediments you may have seen at Electron, Washington.

Questions:

  • What are the major layers of sediment in this outcrop?  To answer this question make a drawing of the outcrop and label the layers.
  • What are the characteristics of the sediment in each layer?  To answer this question, describe the shape, size, and ranges of sizes (sorting) of the sediment in each layer on your drawing.
  • How are the layers different from one another?
  • Do they change as you move sideways?
  • Are we looking are one mudflow or two?

 

 

Activity – Interpreting mudflow deposits II

Move to Mud Mountain Dam, Washington Viewpoint 4.  Once there slowly turn right from azimuth 350° to 000°.  Return to azimuth 350° and click on the green plus sign that appears to get a closer look at the outcrop.

Mud Mountain Dam Washington Viewpoint 4
47°09.38'N / 121°54.12' W / Elevation 335 m (1099 ft)

Background:
This outcrop contains the same mudflow deposits that you saw at Viewpoint 3.  Just like the deposits you saw at that previous viewpoint, these deposits are layered.  Each layer was deposited at different times, and each contains clues about how the flow was moving in this area at the time the sediments were deposited.

Questions:

  • What are the major layers of sediment in this outcrop?  To answer this question make a drawing of the outcrop and label the layers.
  • What are the characteristics of the sediment in each layer?  To answer this question, describe the shape, size, and ranges of sizes (sorting) of the sediment in each layer on your drawing.
  • Which layer do you think is oldest?  Which is the youngest? Why?
  • In which layer was the flood moving the fastest?  In which layer was it moving the slowest?  How did you reach this conclusion?
  • How could you test your answers for the last two questions?

 

White River, Washington

 

Activity – Identifying volcanic hazards in an outcrop

Move to Chinook Pass Highway – State Highway 410 – Viewpoint 1 and turn to azimuth 290°.   Click on the green plus sign to get a closer look at the outcrop.

Chinook Pass Highway - State Highway 410  - Viewpoint 1
47°09.53'N / 121°49.38' W / Elevation 425 m (13494 ft)

Background:
This outcrop is a record of several past volcanic events.  One of these, the Osceola a mudflow, is a debris flow that originated on Mt. Rainier about 5600 years ago.  This mudflow may have been caused by minor volcanic eruption on the mountain that triggered a massive landslide.  Another event is one of the past eruptions of Mt. St. Helens. 

Questions:

  • What layers do you see in this outcrop?  To answer this question make a drawing of the outcrop and label the layers.
  • What are the principle physical characteristics of the material in each layer?  Write these on your drawing.
  • Where are the Osceola deposits?
  • Where are the Mt. St. Helens deposits?
  • How do the deposits compare to each other?  Think about what you observe rather than what you read.
  • What are these deposits and where do they come from?

 

Orting, Washington

 

Activity – Lahar warning sign

Move to Orting, Washington Viewpoint 1 and turn around to azimuth 005°.   Click on the green plus sign that appears to read the sign.

Orting, Washington Viewpoint 1 - Puyallup River Bridge
46°07.74'N / 122°14.15' W / Elevation 33 m (109 ft)

Background:
This sign is part of and emergency warning system developed by the United States Geological Survey in 1998, and now operated by the Pierce County Department of Emergency Management.   The roadway and bridge in the background is one of the major routes into and out of Orting, Washington.

Questions:

  • How high above the valley floor (in meters) do you need to climb to be in the "safe zone"?
  • Based on this sign and the elevation of this viewpoint, what elevation (in meters) do you need to climb to  be in the "safe zone"?
  • Where is the nearest lahar siren from this viewpoint? To answer this question zoom back to the aerial view of Orting, Washington, click on “Map” at the bottom of the frame, and then select the volcanic hazards map from the “Views” directory located in the lower left.

 

 

Activity – Where’s surface of the debris flow

Move to Orting, Washington Viewpoint 2 and turn to azimuth 230°.  Move your cursor over the “Measure” button.

Orting Washington Viewpoint 2 - Puyallup River
47°07.80'N / 122°14.11' W / Elevation 30 m (98 ft)

Background:
Between 1100 and 1200 years ago a debris flow that originated on the west slopes of Mt. Rainier swept down the Puyallup River through Orting.  Deposits left behind by this flow indicate that this flow, called the Electron mudflow, was between 10 and 15 m (33 to 49 ft) deep at this point.  This means that the surface of the river would be 10 to 15 m higher than it is in this scene. 

  Questions:

  • What is the current elevation of the river?
  • How high is the road that passes over the Puyallup River Bridge?
  • If a debris flow like the Electron were to occur today, how far underwater would the road be?

 

 

Activity – Stream deposits and debris flow deposits

Move to Orting, Washington Viewpoint 3 and turn around slowly until you have seen the entire scene.

Orting Washington Viewpoint 3 - Puyallup and Carbon River Confluence
47°07.84'N / 122°13.97' W / Elevation 30 m (98 ft)

Background:
This place is where the Puyallup and the Carbon Rivers.  The rivers left the sand, gravel, and cobbles on the beaches as they flowed west toward the Puget Sound. 

Questions:

  • Where on the beach is the big sediment (the gravel and the cobbles)? To answer this question, give a direction and an elevation, as well as a short description (for examples next to the water, higher up on the beach, where the two river meet, etc.).
  • Where on the beach is the finer sediment (the sand)?
  • Why do you think the big and small sediment appears in different places?
  • What are the shape of the cobbles? Cobbles are big gravel, about the size of your fist.
  • Why do they have this shape?

 

 

Activity – Lahar warning siren

Move to Orting, Washington Viewpoint 4 and turn to azimuth 140° and click on the green plus sign.  Click on the green plus sign that appears to see and hear the lahar warning siren.

Orting Washington Viewpoint 4 - Ptarmigan Ridge Intermediate School
46°06'19.6"N / 122°13'3.9"W / Elevation 50 m (164 ft)

Background:
This siren is part of an automated warning system located in the Puyallup River Valley. In the event of a debris flow, acoustic monitors near Mt. Rainier detect lahar movement and transmit this information, triggering warning sirens throughout the valley.  An acoustic monitor is a device that is very similar to a seismograph that is used for detecting earthquakes.

Questions:

  • How does the test sound of the siren compare to the warning sound?
  • Why were the two sounds designed to be different?
  • In the event of a warning, how high above the valley floor do you need to climb to be in the "safe zone"?  You may need to return to Orting, Washington Viewpoint 1 to look for the sign that gives you this information.
  • Once the siren sounds, how much time do you have to reach the safe zone? Assume that the siren sounds when the leading edge of the debris flow is about 45 km from Viewpoint 4.  Also assume that debris flows travel between 40 to 50 kph (kilometers per hour).
  • What route would you take to get out of the hazard zone, and how long would it take to travel that route?

 

 

Activity – Examining excavated logs

Move to Orting, Washington Viewpoint 4 and turn around to azimuth 160°.  Click on each the green plus signs to looking closely at the logs lying on the lawn.

Orting Washington Viewpoint 4 - Ptarmigan Ridge Intermediate School
46°06'19.6"N / 122°13'3.9"W / Elevation 50 m (164 ft)

Background:
These stumps were unburied during the construction of Ptarmigan School.  Numerous other logs like this have been dug up during other construction projects in the area, indicating that the Puyallup River Valley has been flooded by large debris flows several times in the past 6000 years.  Rocks found with these logs indicate that Mt. Rainier has been the source of these flows.

Questions:

  • How do the two logs compare to each other?
  • What do you think this area looked like before the logs were buried?
  • Find a viewpoint on Mt. Rainier that you think shows what Orting may have looked like after the last major mudflow (about 1500 AD)