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Rock Armor for Harrow Bay: The Rock Cycle at a Stormy Coast

Grade 7 earth science: a rock tumbler test and offshore sand data help a coastal town plan for storms and model the rock cycle's energy sources.

Grade 7ScienceInteractive · Printable

Aligned toMS-ESS2-1

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
11 questions
Classroom-ready

Details

Format: Interactive · Printable
Grade: Grade 7
Subject: Science
Question types: Fill in the blank, Multiple choice, Circle the answer, Sorting, Short answer

About this worksheet

What students practice

Students analyze a rock tumbler investigation to compare how fast different rocks wear down.
Students model how a cliff's sand cycles back into rock and name the energy source behind each step.

How to use

Use during a rock cycle unit; if you have a rock tumbler, show it first, then let students work through the tables and finish with the model argument.

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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Rock Armor for Harrow Bay: The Rock Cycle at a Stormy Coast

Test which rock stands up to waves, then follow a sea cliff's sand through the rock cycle.

Testing rock for the riprap

Read the passage and Table 1, then answer the questions.

Getting Ready for Storm Season

1Harrow Bay is a fishing town at the foot of a tan sandstone cliff, and Coast Road runs along the top of it. Big waves form when strong winds blow across the ocean for many hours, and winds blow because the Sun heats some parts of Earth's surface more than others. During winter storms, waves pound the base of the cliff, break off sand grains and chunks of rock, and carry them away. After two storms last winter, the town decided to protect the base of the cliff with riprap: a wall of large boulders that takes the beating instead of the cliff.

2The sandstone holds clues to its own past. It is made of rounded sand grains cemented together, and some of its layers contain fossil shells and ripple marks like the ones on the sandy sea floor near the beach today. Yet the top of the cliff stands about 30 m above sea level. Geologists say that slow forces inside Earth, powered by heat from its interior, have been raising this coast for a very long time.

3The town can buy boulders of four kinds of rock: sandstone from the cliff itself, shale from a road cut, basalt from an old lava flow and granite from a quarry in the hills. The granite has large, interlocking crystals that grew as magma cooled slowly deep underground. Erosion of the rock above it over millions of years left it at the surface. Ms. Henrietta Lindgaard's seventh-grade class tested which rock wears down slowest. For each rock, students put a 200 g sample in a rock tumbler with 1 L of water and 50 g of coarse grit and ran it for 48 hours. Then they dried and weighed the sample. They ran three trials for each rock, with a new sample each time. The turning barrel knocks the rocks against each other and the grit, a bit like waves knocking stones together on a beach.

4To learn where the worn-away cliff goes, the state geological survey keeps a sediment trap on the sea floor about 1 km offshore, in calm water below the reach of most waves. Each spring, scientists measure the layer of new sand that settled there over the winter. Layers like these are slowly buried by more sediment. Over very long times, the weight of the layers above packs the grains together, and minerals left by the water cement them into solid rock.