Worksheet

Through the Mountain: Rock Cycle Clues From Westbury's Water Tunnel

Grade 7 earth science: a city's water tunnel log and cemetery headstones show how rock changes form and what energy drives the rock cycle.

Grade 7ScienceInteractive · Printable

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1 NGSS standard
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13 questions
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Format: Interactive · Printable
Grade: Grade 7
Subject: Science
Question types: Fill in the blank, Multiple choice, Matching, Circle the answer, Short answer

About this worksheet

What students practice

Students use tunnel rock and temperature data to explain how heat from Earth's interior changes rock.
Students use weathering data to explain how energy from the Sun breaks rock down.
Students model how one rock material can cycle into other kinds of rock.

How to use

Read the passage together and point out the two tables first. Students can work in pairs on the first two sections and write the final explanation on their own.

Curriculum

NGSS standard covered

MS-ESS2-1

Model the cycling of Earth's materials and the energy that drives the rock cycle.

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Through the Mountain: Rock Cycle Clues From Westbury's Water Tunnel

Use a tunnel rock log and old headstones to model how rock changes and what drives it.

Inside the water tunnel

Read the passage and study Table 1. Then answer the questions.

A Tunnel, a Plan and a Cemetery

1The city of Westbury is growing, and its planners have two big projects. A new 12 km water tunnel will carry water from a reservoir on the far side of Pike Mountain to the city's treatment plant. The planners also hope to use the warm water that seeps into the tunnel to heat buildings near its entrance. As the boring machine cut through the mountain, geologist Dr. Ottilie Grunwald logged the rock and measured the temperature of the tunnel wall (Table 1). The east half of the tunnel passes through the same rocks in reverse order. Before the water was let in, seventh graders from Westbury Middle School toured the tunnel with her.

2Dr. Grunwald explained that the shale near the entrances formed from mud that settled on an ancient sea floor, and some of its layers hold fossil shells. Farther in, the rock changes. Slate, schist and gneiss are metamorphic rocks: they formed when older rock was heated and squeezed deep underground but did not melt. Lab tests show that shale usually turns into slate at about 250 to 300 °C, slate turns into schist at about 450 to 500 °C, and schist turns into gneiss at about 600 to 700 °C. As the rock changes, new crystals grow, and they often line up in bands. At about 700 °C or more, rock that holds a little water can begin to melt into magma.

3The granite in the middle of the mountain cooled slowly from magma several kilometers underground. Today all of these rocks lie at or near the surface. Forces powered by Earth's hot interior pushed this region upward, and over millions of years, rain, ice and streams wore away the rock that once covered them. The temperature of rock goes up with depth, so the tunnel wall is warmest where the most rock lies above it.

4The city also has a 150-year-old cemetery with headstones made of four kinds of stone (Table 2). Marble is a metamorphic rock that forms from limestone. Westbury's rain is slightly acidic, so it slowly dissolves marble, while frost and rain break the other stones into tiny grains. Rainwater washes the worn bits into Pike Creek, which carries them, some as solid grains and some dissolved, all the way to the sea. In the sea, animals such as clams use dissolved minerals from the water to build their shells.

Table 1. Tunnel log, west entrance to the middle
Distance in (km)	Rock	What it looks like	Rock above (m)	Wall temp. (°C)
1	Shale	Gray, soft, thin layers, fossil shells	200	14
2	Slate	Dark gray, hard, splits into flat sheets	400	18
3	Schist	Shiny mica flakes in wavy bands	800	26
4	Gneiss	Light and dark bands, large crystals	1200	34
5	Granite	Large crystals fit together, no bands	1600	42

Use Table 1 and paragraph 2. Which statement best describes how the rock changes from km 1 to km 4, moving toward the granite?

A. The fossils disappear, and the rock gains crystals that line up in bands.
B. The rock turns from a banded crystal rock into a soft, layered mud rock.
C. The rock gets softer, and its fossil shells get larger and easier to see.
D. The rock keeps its thin mud layers, but it slowly gets lighter in color.

Use Table 1. From km 1 to km 5, the rock above the tunnel increases by 1,400 m.

On average, the wall gets °C warmer for each extra 100 m of rock above it.

The planners want to heat buildings with water that seeps into the tunnel. Water dripping in near km 5 is much warmer than water dripping in near km 1. Which explanation fits the passage best?

A. Near km 5 the granite is still melted magma, and the water flows over its hot surface.
B. Near km 5 the water comes straight from the reservoir, which summer air has warmed.
C. Near km 5 the water seeps through deeper rock, which is warmed by Earth's interior.
D. Near km 5 the water crosses the sunny mountaintop first, so sunlight warms it more.

Suppose rock keeps warming with depth at the rate you found in question 2, starting from 10 °C at the surface. (Table 1 fits this rule.) Paragraph 2 says slate turns into schist at about 450 °C. (1 km = 1,000 m)

About how many kilometers deep would rock need to be to reach 450 °C? km

Use your answer to question 4. The schist at km 3 formed at about 450 °C, yet today only 800 m of rock lies above it. Which explanation fits paragraph 3 best?

A. Rising magma broke off pieces of schist and dropped them high inside the mountain.
B. The schist formed near the surface when summer sun baked the slate for many years.
C. One large earthquake lifted the schist many kilometers to its place in a single day.
D. Inner forces slowly raised the rock, and erosion wore away many kilometers of rock above it.

The slate at km 2 formed from the same shale layers that hold fossil shells at km 1, yet the slate has no fossils. Which explanation fits the passage best?

A. Heat and pressure grew new crystals in the rock, and the shells were wiped out.
B. The boring machine crushed the shells in the slate as it cut the tunnel.
C. Groundwater seeping into the new tunnel dissolved the shells out of the slate.
D. The slate formed from lava that cooled on top of the old sea floor mud.

Stone in the city

Use Table 2 and paragraph 4. Every headstone in the table has stood in the open for 150 years.

Table 2. Lettering worn away on headstones in 150 years
Stone	Kind of rock	Worn away (mm)
Marble	Metamorphic (from limestone)	4.5
Sandstone	Sedimentary	2.4
Slate	Metamorphic (from shale)	0.6
Granite	Igneous	0.3

On average, how many millimeters of lettering did the marble headstones lose every 100 years? mm

The marble lost how many times as much as the slate? Do not round. times as much

Rain and frost wore away the lettering on the headstones. Which energy source mainly drives the rain and frost?

A. Warm tunnel water, which rises through the hill as clouds of steam
B. The weight of each headstone, which presses water into its stone
C. Heat from Earth's interior, which warms the cemetery soil from below
D. Energy from the Sun, which evaporates water and drives the weather

10.

Pike Creek carries worn bits of marble, some dissolved, to the sea. Which path could this material follow next in the rock cycle, based on the passage?

A. Dissolves in the sea → turns into lava → cools into slate → crumbles into fossil shells
B. Built into shells and lime mud → buried and cemented into limestone → heated into marble
C. Melted by sunlight in the sea → cooled into granite → buried as mud on the sea floor
D. Settles on the sea floor → becomes gneiss within a few years → washed back up the creek

Modeling the rock cycle under Pike Mountain

Use the whole passage and both tables.

11.

Use paragraphs 2 and 3. Match each rock in the tunnel to what it formed from.

Slate
Schist
Gneiss
Granite
Shale

A. Schist
B. Mud on a sea floor
C. Magma
D. Shale
E. Slate

12.

Circle the three steps that are driven mainly by heat from Earth's interior.

Frost cracking granite on the mountaintopShale changing into slate deep undergroundRain dissolving a marble headstonePike Creek carrying grains to the seaRock melting into magma deep undergroundPike Mountain slowly being pushed upward

13.

A city council member says, "The rock inside Pike Mountain and the stone in our cemetery have nothing to do with each other. Rock just stays the kind of rock it is." Do you agree? Make a claim, use evidence from Table 1 and Table 2, and explain your reasoning with a model of the rock cycle. Name the energy source for at least two steps.