Ryan Hill
GEOS 401
10/22/02
Lesson: Rock Cycle-Focus on Sedimentary Rocks
I. Purpose
The purpose of this lesson is to introduce students to the sedimentary rock portion of the rock
cycle and learn how to identify sedimentary rocks based on observable properties. Sedimentary
rock formation is important to understand relates to the dynamically changing geosphere through
weathering, erosion, and chemical processes.
Standards
Content Standard D
1) Some changes in the solid earth cell can be described as the rock cycle. Old rocks at
the Earth’s surface weather, forming sediments that are buried, then compacted,
heated, and often recrystallized into new rock. Eventually, those rocks may be
brought to the surface by the forces that drive plate motions, and the rock cycle
continues.
2) Movement of matter between reservoirs is driven by Earth’s internal and external
sources of energy. These movements are often accompanied by a change in the
physical and chemical properties of the matter.
II. Big ideas
1) The rock cycle relates all types of rocks on Earth together through specific processes.
2) Rock types, in the broad sense, are defined based on their mode of formation.
3) Sedimentary rocks are rocks that form through the burial and lithification of sediments.
4) Further classification of igneous rocks is done through the recognition of different
physical and chemical properties, such as mineral composition, texture, place of origin,
and silica content.
Prior Knowledge
1) Useful properties in identifying minerals
2) Physical and chemical structure of the Earth
3) Properties of rocks
III. Connections to the real world
1) Ocean waves are often seen crashing into rocks on islands or shorelines. This breaks
chunks of rock away, which are transported, deposited, and buried.
2) Burial of rock and organic material leads to the formation of coal, which is a major
source of power in our technological society.
IV. Objectives
1) Students will be able to explain what sedimentary rocks are and where they form.
2) Students will describe the various properties and classifications of sedimentary rocks.
V. Assessment instruments
The lesson includes an activity that will demonstrate to students how sedimentary rocks form.
This activity includes questions for the students to answer. Students will also classify different
sedimentary rock samples based on the properties that they observe. Answers to all questions
will be answered on paper.
VI. Activities
Introduction
Review what the rock cycle is, showing the rock cycle diagram. Review with the students what
they learned about igneous rocks. Pose a scenario to the class. Describe a volcanic eruption that
has occurred on an island. Over time, water begins to incise through the newly formed rock,
forming a stream. Ask the students what they think water and increasing stream size will do to
the newly formed rock over time. Describe how this is one scenario that can lead to the
formation of sedimentary rocks, which form from the burial of rock particles that were
weathered and eroded away from a previous source and deposited. (The description of this
specific scenario is meant to help students relate their previous experience with igneous rocks to
the formation of igneous rocks.) The continual deposition of more sediments leads to the
compaction and cementation of the sediments previously deposited.
Activities
Ask students to list out possible ways for existing rock to be weathered and eroded. These should
include rain, streams, rivers, oceans, wind, chemical weathering, etc. Conclude that there are
many processes at work that serve to break down existing rock and transport the sediments.
Show the class an example of a layered sedimentary rock. Ask them how they think the
sediments became layered. Tell them that they are going to conduct an activity that will
demonstrate how layered sedimentary rocks form. Divide the class up into groups of four. Pass
out all the supplies and the instructions for the activity “How do sedimentary layers form?” Help
the students complete the activity and answer the questions.
Day 2
Introduction
Review with the class the activity they completed the previous day. Ask them how sedimentary
layers form. Tell students that they will now learn how to classify sedimentary rocks in a way
similar to igneous rocks.
Activities
Have students get into the same groups of four from the previous day. Define sedimentary rock
types clastic, organic, and chemical. Have students name each sample of rock based on the
definition they were just given and explain what they observed in order to reach their conclusion.
Work on further classifying clastic rocks. Define conglomerates and breccias, sandstones, and
shales. Have the students classify the clastic rock samples in front of them to their appropriate
name.
Define Organic rocks. Have them classify their organic samples as coal, limestone, or chalk.
Define chemical rocks. Have students classify their samples as halite or gypsum. They may
recall these names from the minerals lesson. This is a good place to explain to them the
relationship between minerals and rocks, as they may be confused as to how a mineral and rock
have the same name.
Also have students check on the progress their sedimentary layers formation activity from the
previous day. Have them write down any differences they see in their sample.
Conclusion
Have students describe what defines a clastic, organic, and chemical sedimentary rock. Ask them
to write down any areas that remain unclear to them.
VII. Materials
1) Diagram of rock cycle
2) Instructions for “How do sedimentary layers form?” activity.
3) Worksheets with tables for observations for this activity
4) 8-10 medium-size jars
5) Graduated cylinder
6) 1 kg each of gravel, sand, and clay
7) 8-10 spoons
8) 8-10 cups
9) 1 box of toothpicks
10) 1 L of diluted white glue solution
11) 8-10 stopwatches
Day 2
12) 8-10 samples each of conglomerate, breccia, sandstone, shale, limestone, coal, chalk,
halite, and gypsum
13) Worksheet to write their observations down on.
Note: “How do sedimentary layers form” activity is an activity that can be found on page
225 of the following textbook:
DiSpezio et al. Science Insights: Exploring Earth and Space. Addison-Wesley Publishing,
1996.