Tephra Explorer

2 cm Grade Level: 6–9 Overview 5 cm Mount Rainier 5 cm Students view distribution patterns of tephra

2 cm layers found around Mount Rainier and discover their source. Learner Objectives: Students will: ● Understand general distribution Vocabulary: Isopach, pumice, scoria, patterns of tephra dispersal by wind silica, tephra, volcanic ash at Mount Rainier ● Understand how to interpret an isopach map Skills: Prediction, interpretation, map reading ● Recognize that some tephra at Mount 1 Rainier originated at other Cascade volcanoes Benchmarks:

Setting: Classroom See benchmarks in Introduction.

Timeframe: 50 minutes (or 1 class session)

Materials: Explorer Tephra ● Copies of “Make Your Own Tephra Isopach Map” student page ● Graphic of “Exploring Tephra Layers at Mount Rainier”—

Tephra Maps 1 through 6 Chapter 2 ● Projection copy or student copies of “Exploring Tephra Layers at Mount Rainier”

● Map of Cascades Volcanoes

NATIONAL PARK SERVICE

Living with a Volcano in Your Backyard- An Educator's Guide with Emphasis on Mount Rainier Prepared in collaboration with the National Park Service U.S. Department of the Interior U.S. Geological Survey General Information Product 19 Activity last modified: September 5, 2014 Tephra Explorer-continued . . .

Teacher Background Tephra is a general term for fragments of rock and lava regardless of size that are blasted into the air by explosive eruptions. Tephra includes large rocks and small fragments, such as scoria, pumice and volcanic ash. At Mount Rainier, tephra is conspicuous as sandy material in colorful shades of orange, tan, yellow, gray, brown and white. Each tephra layer represents an eruptive event.

During an eruption, large pieces of dense rock, pumice and scoria drop on the slopes of the volcano while volcanic ash often remains aloft and is transported laterally. When volcanic ash and surrounding air cools, and air speed is insufficient to support it, the ash drops to the ground and forms a layer often in the shape of an elongated oval.

While Mount Rainier is the source for at least 40 recognizable tephra layers, not all of the tephra found within Mount Rainier National Park originated there. Wind carried volcanic ash 2 from eruptions at Mount St. Helens to the slopes of Mount Rainier on at least two occasions, once between 3,700 and 3,800 years ago and in A.D.1480 (layers Yn and W respectively), and from ancient Mount Mazama (Crater Lake) in Oregon to broad regions of the Pacific Northwest around 7,700 years ago (layer O).

These rogue layers puzzled early researchers who found the ash in unexpected locations and who recognized that their chemical composition differed from rocks at Mount Rainier. By carefully mapping the thickness of each ash layer, geologists were able to see that the ash Explorer Tephra layer thickened away from Mount Rainier and thereby were able to trace the ash and pumice to its source. They confirmed their hypothesis, thereby matching the chemical composition of the tephra layers with their volcanic origin.

Far-traveled tephra from Mounts St. Helens and ancient Mazama have a silica content that Chapter 2 typically ranges between 62 and 67 percent. Tephra from these two volcanoes appears white, gray, tan or orange in color. Mount Rainier rocks and tephra contain 55 to 64 percent silica. Its tephra typically appears darker in color than tephra from Mount St. Helens and Mount Mazama. Tephra Explorer-continued . . .

See “Volcano Fan Club” for more information on clues geologists use to interpret tephra layers.

See “Tephra Popcorn” for details about different types of tephra.

The “Soda Bottle Volcano” activity describes how tephra is formed.

Isopachs 1 3

Geologists measure the thickness of a tephra layer and note its grain size in numerous locations, then record thickness values on a map. Later, they draw lines of equal thickness called isopachs, in the same way that elevation is portrayed with contours on a topographic map. With an isopach map in hand, they can trace the layer to its thickest point on the slopes of the source volcano. Tephra Explorer Tephra

How Do They Name Chapter 2 2 Tephra Layers at Mount Rainier?

At Mount Rainier, tephra layers are named using letters of the alphabet (Tephra O, Tephra Y, Tephra C, etc...). The letters are not in alphabetical order because when geologists first studied tephra layers at Mount Rainier, they did not know how many layers they would find. They named the layers after physical characteristics such as color. For example: Tephra O for orange, Tephra W for white, and Tephra Yn for yellow. Tephra Explorer-continued . . .

Procedure Exploring Tephra Layers at Mount Rainier

Determine the origin of tephra layers on the flanks of Mount Rainier by studying maps and developing hypotheses based on tephra thickness and distribution. These tephra layers are some of the most prominent layers observable by visitors on the south side of Mount Rainier National Park.

1. Before class begins, determine whether you wish to project maps for all-class viewing or distribute a set of maps to each student or student group, and then make preparations. All students should receive a copy of the student page “Make Your Own Tephra Isopach Map.”

2. Tell students that some tephra layers on the flanks of Mount Rainier originated at 4 other volcanoes and explain how this at first perplexed geologists who assumed that the tephra had erupted from Mount Rainier. Explain to students that they will observe maps of tephra layers at Mount Rainier. Encourage them to develop hypotheses about how wind direction influences the pattern of tephra fallout.

3. Begin (and end) the activity with the “Tephra Isopach Map” student page, where students read that at Cascade volcanoes, the prevailing direction of air flow is towards the east,

northeast, or southeast approximately 85 percent of the time. They are instructed to draw Explorer Tephra a hypothetical tephra layer—a partly teardrop shape that delineates the outermost limit of a recognized tephra layer. This tephra layer originates at the summit crater and extends away from the volcano, as blown by prevailing winds. Be sure that students recognize this as a vertical view, with the observer looking down upon a tephra layer on the ground. This step should advance students’ understanding of the general pattern of tephra fallout at volcanoes, and help them to interpret tephra maps 1 and 2. Chapter 2

4. “Instruct the students to draw circles (contours) to separate the zeros from the ones, the ones from the twos, the twos from the threes, and the threes from the fours (see example on teacher page 10). These contours indicate areas of equal tephra thickness, known as isopachs. Explain that a tephra isopach map is a standard tool used by geologists who study volcanic eruptions.

5. Use overhead projection to display tephra maps 1 through 6 or provide paper copies to each student or student group. For each map, students should identify the wind direction at the time of the tephra eruption and a probable source volcano. Students should make note of the location of their community relative to the probable volcanic source and assess whether tephra from each eruption has fallen there. Use the "Map of Cascade Volcanoes" as a guide to this investigation. Tephra Explorer-continued . . .

6. Promote further discussion about what happens when the wind direction changes during the course of an eruption or when rising tephra reaches atmospheric levels where winds blow in opposing directions. Tephra fallout patterns can become complex, such as during the eruptions of Mount St. Helens in the 1980s, when complex atmospheric conditions resulted in complicated small-scale patterns of tephra fall across Washington State.

7. Return to the student page “Make Your Own Tephra Isopach Map.” Instruct students to use a different color marker or pen to add to their student page maps, by drawing 3 to 5 hypothetical isopachs for a potential future tephra fall on Mount Rainier from a large eruption at Crater Lake. (Isopachs should appear as curved lines from the south, with decreasing thickness towards the north.) Provide additional scenarios for students’ drawing of isopachs, such as the pattern of a tephra layer that results from easterly winds (which would result with a teardrop shape facing west). 5 8. Invite discussion about how this information can assist geologists who investigate a volcano’s history and hazards. Explore the types of information that geologists can obtain from these maps, such as the volcanic source, area and volume of tephra erupted, and wind direction at the time of eruption.

9. Lead a discussion of energy transformation, where rising tephra gains potential energy as it rises and looses energy as it falls.

Explorer Tephra Optional: Provide students with information about some Pacific Northwest tephra layers by distributing the information on the teacher pages.

Adaptations Chapter 2

◆ Use protractors with your study of tephra layers. Provide students with protractors and instruct them to determine precise compass directions of tephra fall for the "Tephra Maps," 1 through 6. For the student page "Make Your Own Tephra Isopach Map," choose some compass directions in degrees and instruct students to produce a tephra layer on the axis of the compass directions provided. Explore together what regions or communities would be affected by these hypothetical tephra eruptions. Tephra Explorer-continued . . .

Extensions

◆ Students Research the Tephra Layers Discussed in this Activity. Students conduct a library or Internet search for information about the tephra layers discussed in this activity.

◆ Use kitchen ingredients to make a cross-sectional representation of tephra layers stacked one upon the other. Assemble cornmeal, cinnamon, oatmeal, flour, decorative sprinkles, and different colors of sugar, paper and glue sticks.

1. Students draw a rectangle across one-half of a piece of construction paper. 2. They take a pinch of each ingredient, and glue it on the paper from the bottom of the rectangle to the top. Each ingredient represents a layer of tephra. 3. Students should label each layer, and then while observing the width of each layer on the paper and its relative particle size, add a few words about the eruptive 6 event, such as “large eruption,” “short eruption,” “tephra from nearby eruption” and “tephra from far away.”

Tephra Layers Tephra Explorer Tephra ◆ Cinnamon - .3 cm tephra from volcano far away ◆ Decorative sprinkles - .4 cm tephra from volcano far away ◆ Cornmeal - 3 cm tephra from a large eruption Chapter 2 ◆ Flour - 6 cm tephra from a large eruption far away

◆ Sugar - 15 cm tephra from a large eruption far away Tephra Explorer-continued . . .

Assessment

Look for students’ understanding of the following concepts: 1) that wind disperses tephra; 2) tephra particle sizes are greatest near the volcano; 3) some tephra on the slopes of one volcano might have erupted from a different volcano. Students should understand that tephra layers provide a valuable record of previous eruptions. Students might indicate that this knowledge helps scientists determine the kinds of eruptions that happen at a given volcano, and ultimately the most likely eruption types for the future. Understanding what types of eruptions can happen in the future ultimately saves lives and property and improves the well being of nearby communities.

References 7 Mullineaux, D.R., 1974, Pumice and other pyroclastics in deposits at Mount Rainier National Park: U.S. Geological Survey Bulletin 1326, 83 p.

Crandell, D.R., 1969, Surficial geology of Mount Rainier National ParkW ashington: U.S. Geological Survey Bulletin 1288, 41 p.

Refer to Internet Resources Page for a list of resources available as a supplement Explorer Tephra to this activity. Chapter 2 Make Your Own Tephra Isopach Map

In the vicinity of the Cascade volcanoes, the prevailing direction of air flow (wind) is towards the east, northeast, or southeast approximately 85 percent of the time. Based on this information, make a prediction about the direction of tephra travel during an eruption of Mount Rainier. Draw a wind arrow on the map below.

121˚55' W 121˚45' W 121˚35' W 47˚ N C a

rb r

o e

n v i R

iv R e r 0 8 0 0 0 e 0 0 0 t 0 0 0 i 0 0 0 0 0 0 0 Sunrise Visitor h 0 1 W 0 0 Center 1 0 0 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 0 2 2 1 0 2 2 2 2 2 2 1 1 0 0 3 2 1 1 0 0 0 3 3 3 3 3 2 2 1 1 0 Mount Rainier 3 2 2 1 3 3 2 2 1 1 0 4 4 3 2 1 0 Summit 4 4 3 2 1 0 4 4 4 3 2 2 0 crater 3 2 2 1 0 3 1 3 3 3 2 2 Explorer Tephra 3 3 3 3 3 2 0 3 O 2 2 1 0 3 3 3 3 han 1 0 ap 2 0 0 1 2 e 1 2 c 2 1 0 0 2 2 o 1 0 0 1 1 s 0 0 Paradise 1 h 1 0 0 Visitor Center0 1 1 1 1 1 0 k 0 0 R 11 1

e i

e 0 1 v 0 0 e

r 0 00 0 0 r C 0 0 MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT 0 0 0 0 tz 0 u 0 a 0 0 0 46˚45' N K 0 0 0 Chapter 2 166

0 5 10 KILOMETERS

Modified from Mullineaux, 0 5 10 MILES 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS

1. Develop an hypothesis that explains how the thickness of tephra fall will vary with increasing distance from the volcano.

2. Draw circles (contours) to separate the zeros from the ones, the ones from the twos. the twos from the threes, and the threes from the fours. These contours indicate areas of equal tephra thickness and are known as isopachs.

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Make Your Own Tephra Isopach Map

121˚55' W 121˚45' W 121˚35' W C 47˚ N a

rb r

o e

n v i

R Wind Direction i R v e r 0

0 e 0 t 0 0 0 0 0 i 0 0 0 0 0 0 0 h 0 W 0 Sunrise Visitor 1 0 0 0 Center 1 0 0 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 9 0 2 2 2 1 0 2 2 2 2 2 1 1 0 0 2 1 1 0 0 0 3 3 3 3 3 2 2 1 0 Mount Rainier 3 2 2 1 3 3 2 1 1 1 4 4 3 2 2 0 0 Summit 4 4 3 2 1 1 0 4 4 4 3 2 2 0 0 crater 3 2 2 1 3 3 3 3 3 2 2 1 3 3 3 3 0 3 Oh 2 2 1 0 3 3 3 3 an 2 1 0 ap 1 e 2 1 0 0 2 2 c 2 0 0 2 2 o 1 1 1 s 0 1 h 0 0 Paradise 1 1 0 0 Visitor Center 0 1 1 1 R 1 1 1 0 Explorer Tephra k 0 i 11

e v e 0 e

r 0 1 0 0 r 00 C 0 0

MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT 0 0 tz 0 0 0 0 0 u 0 a 0 0 0 0 46˚45' N K 0 0 166

0 5 10 KILOMETERS Chapter 2 0 5 10 MILES Modified from Mullineaux, 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS

1. Develop a hypothesis that explains how ash thickness will vary with increasing distance from the volcano. ANSWER: The deposit will be thickest close to the volcano and thinner farther from the volcano.

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier

Instructions: On Tephra maps 1 through 6, identify the wind direction at the time of the tephra eruption and the probable source volcano.

130˚ W 120˚ W 110˚ W

ALBERTA SASKATCHEWAN Tephra Map 1

BRITISH Approximate Edmonton COLUMBIA limit of recognized Wind Direction:______50˚ N ash Calgary 10 Kamloops Source Volcano:______Mount Baker CANADA WASHINGTON Glacier Peak UNITED STATES Seattle Mount Rainier Mount St. Helens MONTANA Mount Hood OREGON <15 cm

IDAHO Explorer Tephra Crater Lake (site of Mount Mazama)

Mount Shasta WYOMING 40˚ N UTAH Lassen

CALIFORNIAPeak NEVADA Chapter 2

0 100 200 300 KILOMETERS

0 100 200 300 MILES Modified from Mullineaux, 1974, U.S. Geological Survey Bulletin 1326

Explain your answer below:

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier -continued

Instructions: On Tephra maps 1 through 6, identify the wind direction at the time of the tephra eruption and the probable source volcano.

130˚ W 120˚ W 110˚ W

ALBERTA Tephra Map 2 Minimum Edmonton extent of BRITISH ash Wind Direction:______COLUMBIA

50˚ N Source Volcano:______11 Kamloops Calgary Vancouver

Mount Baker CANADA WASHINGTON Glacier Peak UNITED STATES Seattle Mount Rainier

45˚ N Mount St. Helens Mount Hood Explorer Tephra OREGON IDAHO Three Sisters

Crater Lake (site of Mount Mazama) Chapter 2

0 100 200 300 KILOMETERS Modified from Mullineaux, 1974, U.S. Geological Survey Bulletin 1326 0 100 200 300 MILES

Explain your answer below:

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier -continued

Instructions: On Tephra maps 1 through 6, identify the wind direction at the time of the tephra eruption and the probable source volcano.

121˚55' W 121˚45' W 121˚35' W 47˚ N C Tephra Map 3 a

rb r

o e

n v i R

iv R e r Wind Direction:______e 0 t i Sunrise Visitor h W Center 2 Source Volcano:______12 5

Mount Rainier

Summit crater 15 10 O ha na pe c 5 o Paradise s h

Visitor Center 2 Explorer Tephra k R e i e v

r 0 e C r z MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT t u a 46˚45' N K

166

0 5 10 KILOMETERS Chapter 2

Modified from Mullineaux, 0 5 10 MILES 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS

Explain your answer below:

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier -continued

Instructions: On Tephra maps 1 through 6, identify the wind direction at the time of the tephra eruption and the probable source volcano.

121˚55' W 121˚45' W 121˚35' W 47˚ N C a Tephra Map 4

rb r

o e

n R v i i v 7.5

e R r 2 5 Wind Direction:______0 e 1 t i

0 h Sunrise Visitor W 7.5 13 Center Source Volcano:______15

Mount Rainier Summit crater 30 10 O han 5 ap e c o s Paradise h Tephra Explorer Tephra Visitor Center R k i e v e e

r r C 2 MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT z t u 0 46˚45' N a K

166

0 5 10 KILOMETERS Chapter 2

Modified from Mullineaux, 0 5 10 MILES 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS

Explain your answer below:

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Explain youranswerbelow: 46˚ 1974, U.S.GeologicalSurveyBulletin1326 Modified from Mullineaux, and theprobable sourcevolcano. Instructions: On Tephra maps1through 6, identifythewinddirection atthetimeoftephra eruption 47˚ 45' 121˚ N N 55' W MOUNT RAINIER NATIONAL PARK BOUNDARY

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 GIP Survey Geological S. U. Guide: Educator's Your in Backyard–An aVolcano with Living K au

z C

C a

r - Tephra Rainier Layers at Mount Exploring

re b

e o

k n continued

crater Summit Visitor Center Paradise Mount Rainier

v e r 121˚ 45' W 0 0

Center Sunrise Visitor

CONTOUR INTERVAL INCENTIMETERS

15 2

5 a

166 5 n

5 a

e 121˚

10 KILOMETERS R r i v e 35'

W W hit e River 10 MILES Source Volcano:______Wind Direction:______Tephra Map5 14 Chapter 2 Tephra Explorer Explain youranswerbelow: 46˚ 1974, U.S.GeologicalSurveyBulletin1326 Modified from Mullineaux, and theprobable sourcevolcano. Instructions: On Tephra maps1through 6, identifythewinddirection atthetimeoftephra eruption 47˚ 45' 121˚ N N 55' W MOUNT RAINIER NATIONAL PARK BOUNDARY A pp ro K x a im Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 GIP Survey Geological S. U. Guide: Educator's Your in Backyard–An aVolcano with Living a u te

C li C

r m a

e it r - Tephra Rainier Layers at Mount Exploring

e b

k o

o continued crater Summit n Visitor Center Paradise Mount Rainier f

c R

o v e gn r iz e 121˚ d la ye 45' r W 0 0 Center Sunrise Visitor CONTOUR INTERVAL INCENTIMETERS 2

h a

166

5 n

5 a

p 121˚

10 KILOMETERS h

R r i e v 35'

W W hit e River 10 MILES Source Volcano:______Wind Direction:______Tephra Map6 15

Chapter 2 Tephra Explorer Exploring Tephra Layers at Mount Rainier—Answers

130˚ W 120˚ W 110˚ W

ALBERTA SASKATCHEWAN Tephra Map 1

BRITISH Approximate Edmonton COLUMBIA limit of recognized Wind Direction:______50˚ N ash Kamloops Calgary Source Volcano:______

Mount Baker CANADA WASHINGTON Glacier Peak UNITED STATES Seattle Mount Rainier 16 Mount St. Helens MONTANA Mount Hood OREGON <15 cm IDAHO Crater Lake (site of Mount Mazama)

Mount Shasta WYOMING 40˚ N UTAH Lassen Tephra Explorer Tephra CALIFORNIAPeak NEVADA

0 100 200 300 KILOMETERS Chapter 2

0 100 200 300 MILES Modified from Mullineaux, 1974, U.S. Geological Survey Bulletin 1326

Tephra O: Wind Direction: From Southwest Source Volcano: Ancient Mount Mazama (Crater Lake) Age: 7,700 years ago Description: Tephra layer O originated from ancient Mount Mazama about 400 kilometers (250 miles) south of Mount Rainier, during a cataclysmic eruption that geologists recognize as the largest known eruption in the Cascades during the past 10,000 years. The eruption emptied the magma chamber, which caused collapse of the summit crater and formed a deep depression that filled with water to become Crater Lake. Wind transported the tephra over much of the northern United States and southwest Canada. At Mount Rainier, tephra layer O is generally about 5 centimeters thick (2 inches). Layer O is recognizable in road and trail cuts by its flourlike texture and commonly yellow- orange color. Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier— Answers-continued

130˚ W 120˚ W 110˚ W

ALBERTA Tephra Map 2 Minimum Edmonton extent of BRITISH ash COLUMBIA Wind Direction:______

50˚ N Source Volcano:______Kamloops Calgary Vancouver 17 Mount Baker CANADA WASHINGTON Glacier Peak UNITED STATES Seattle Mount Rainier

45˚ N Mount St. Helens Mount Hood OREGON IDAHO Three Sisters Tephra Explorer Tephra Crater Lake (site of Mount Mazama)

0 100 200 300 KILOMETERS Modified from Mullineaux, 1974, 0 100 200 300 MILES

U.S. Geological Survey Bulletin 1326 Chapter 2

Tephra Yn: Wind Direction: From Southwest Source Volcano: Mount St. Helens Age: 3,700–3,800 years ago Description: Between 3,700 and 3,800 years ago, an enormous eruption at Mount St. Helens, about 80 kilometers (50 miles) southwest of Mount Rainier, erupted the tephra that formed layer Yn. This eruption was many times larger than the well known eruption of May 18, 1980. Layer Yn varies in thickness from 0 to 46 centimeters (18 inches) at Mount Rainier National Park. Layer Yn is recognizable by its grainy texture and light-yellow to brown color.

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier— Answers-continued

121˚55' W 121˚45' W 121˚35' W 47˚ N C a Tephra Map 3

rb r

o e

n v i R

iv R e r

e Wind Direction:______0 t i Sunrise Visitor h W Center 2 Source Volcano:______5 18 Mount Rainier

Summit crater 15 10 O ha na pe c 5 o Paradise s h Visitor Center 2 k R e i e v

r 0 e C r z MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT t Explorer Tephra u a 46˚45' N K

166

0 5 10 KILOMETERS

Modified from Mullineaux, 0 5 10 MILES 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS Chapter 2

Tephra D:

Wind Direction: From West Source Volcano: Mount Rainier Age: 6,600–7,400 years ago Description: Tephra layer D consists of pumice, scoria and volcanic bombs erupted from Mount Rainier between 6,600 and 7,400 years ago. Wind blew this material to the eastern slopes of the volcano, where it exists to a maximum thickness of 15 centimeters (6 inches). Tephra layer D is recognizable by its coarse texture and yellow to red-brown color. This eruption, one of many in this eruptive period, might have been large enough to form lahars in nearby river valleys.

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier— Answers-continued

121˚55' W 121˚45' W 121˚35' W 47˚ N C a Tephra Map 4

rb r

o e

n R v i i v 7.5

e R r 2 5

0 e Wind Direction:______1 t i

0 h Sunrise Visitor W Center 7.5 Source Volcano:______15

Mount Rainier 19 Summit crater 30 10 O han 5 ap e c o s Paradise h Visitor Center R k i e v e e

r r C 2 MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT z t u 0 46˚45' N a K

166 Explorer Tephra

0 5 10 KILOMETERS

Modified from Mullineaux, 0 5 10 MILES 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS

Tephra C: Chapter 2

Wind Direction: From West/Southwest Source Volcano: Mount Rainier Age: 2,200 years ago Description: Tephra layer C is the thickest and most widespread tephra layer of Mount Rainier origin within the park. The tephra fell on mountain’s southern, eastern and northern flanks to a maximum thickness of 30 centimeters (12 inches) near the summit on the eastern flank.T ephra C exists over a broad area, possibly because wind direction fluctuated while the volcano was erupting. The eruption tossed some melon-sized rocks into the air. Winds deposited them 10 kilometers (6 miles) from the volcano! Tephra layer C is coarse-grained and varies in color from nearly-white pumice to dark brown scoria and gray rock fragments. It is coarse grained. Pieces of Tephra C, that are walnut to fist-sized, cover the ground in the vicinity of SunriseV isitor facilities. The eruption that produced layer C was large enough to form lahars in nearby river valleys.

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 Exploring Tephra Layers at Mount Rainier— Answers-continued

121˚55' W 121˚45' W 121˚35' W 47˚ N C Tephra Map 5 a

rb r

o e

n v i R

iv R e r Wind Direction:______

e t i Sunrise Visitor h Center W Source Volcano:______

20 Mount Rainier

Summit crater

Oh 2 ana 5 pe co 15 s Paradise h Visitor Center k R e i e v

r e C r MOUNT RAINIER NATIONAL PARK BOUNDARY PARK RAINIER NATIONAL MOUNT tz 5 u 2 a 46˚45' N K Explorer Tephra

166

0 5 10 KILOMETERS

Modified from Mullineaux, 0 5 10 MILES 1974, U.S. Geological Survey Bulletin 1326 CONTOUR INTERVAL IN CENTIMETERS Chapter 2 Tephra L:

Wind Direction: From Northwest Source Volcano: Mount Rainier Age: 7,200 years ago Description: Tephra layer L erupted from Mount Rainier and covered much of the eastern and southeastern slopes of the mountain. The narrow band of layer L to the southeast indicates that the wind was strong and blew consistently in this direction during the eruption. Tephra layer L is yellowish-brown in color. It contains pumice, ash and volcanic bombs.

Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 because theyfollowedthe tephratrailbacktotheslopesofMountSt.Helens. Helens. Scientistsknow that thistephraisfromMountSt.HelensandNOT Mount Adams, This eruptionalsoformedsmalllavaflowsand pyroclastic flowsontheslopesofMountSt. (310 miles)tothenorth,tephralayer W appearsgray—whiteincolorandhasacoarsetexture. transported towardsthenortheastbywinds.On slopesofMountRainier, 500kilometers Description: Age: Source Volcano: Wind Direction: Tephra W: 46˚ 1974, U.S.GeologicalSurveyBulletin1326 Modified from Mullineaux, 47˚ 45' 121˚ N N

55' Approximately W MOUNT RAINIER NATIONAL PARK BOUNDARY A pp ro Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 GIP Survey Geological S. U. Guide: Educator's Your in Backyard–An aVolcano with Living K x im a u a Tephra layer W was erupted fromMountSt.Helensaround A.D. 1480and te

C li C

r m a r

e it

e b

k o o Mount St.Helens From Southeast crater Summit n Visitor Center Paradise Mount Rainier f

c R

o v 500 yearsago e Answers Tephra Rainier Layers at Mount Exploring gn r iz ed 121˚

la ye 45' r W 0 0 Center Sunrise Visitor CONTOUR INTERVAL INCENTIMETERS - 2 continued

h a

166

5 n

5 a

p 121˚

10 KILOMETERS h

R r i e v 35'

W W hit e River 10 MILES Source Volcano:______Wind Direction:______Tephra Map6 — 21 Chapter 2 Tephra Explorer Living with a Volcano in Your Backyard–An Educator's Guide: U. S. Geological Survey GIP 19 GIP Survey Geological S. U. Guide: Educator's Your in Backyard–An aVolcano with Living Range Coast CALIFORNIA Mountains Olympic Salem Chehalis Portland Longview Redding Klamath Falls Eugene Vancouver, B.C. Map of Cascade Volcanoes of Cascade Map ▲ ▲ Vancouver Three Sisters Bellingham ▲ ▲ ▲ Mount Meager Olympia ▲ ▲ ▲ ▲ ▲ Seattle ▲ Tacoma Everett Mount Garibaldi Mount Shasta Mount St.Helens ▲ ▲ ▲ ▲ ▲ ▲ ▲ ▲ Crater Lake ▲ ▲ ▲ ▲ ▲ ▲ Mount Baker ▲ ▲ ▲ ▲ ▲ ▲ Mount Jefferson Mount Adams Mount Rainier Mount Hood Bend ▲ ▲ Lassen Peak Medicine LakeVolcano ▲ ▲ Newberry Volcano Glacier Peak Yakima Pendleton 0 0 WASHINGTON CANADA Spokane 01010200Kilometers 150 100 50 OREGON 50 USA Scale 100 Miles 22 Chapter 2 Tephra Explorer