Rock Story
The Anishinabe believe that Rocks are our grandfathers and share stories with us.
We can tell stories of how the rock was formed and what happened during its life by observing the rock and learning from it.
Explore
Investigate some Indigenous stories revolving around rocks. Click on this link or the picture.
Activity
Make a comic or drama about the story of a rock of your choice (that you found, identified, or discovered on this site). Be sure to include how the rock formed, any erosion that may have happened, as well as how it got there (location). Be creative. Give your rock a name. Include time period in millions of years if you can. Use the information below to help you. PDF summary and handout here.
What happened to your rock?
Use the evidence below to write the story of your rock:
Rock Story Chart
See below for more details in each category. Summary in picture to the right. Handout PDF here or click on the picture.
Students can use this infographic to help them with their story on their rock comic, rock drama, or rock story.
Location
The bedrock around Toronto is sedimentary. If the rock you have is sedimentary, it would have broken off of the local bedrock through erosion, trees, ice, or fracture (or human caused - construction).
If a local rock you found in Toronto is igneous or metamorphic it must have come from either Humans or Glaciers. Glaciers can drop off huge boulders hundreds of kilometers. Humans transport boulders and gravel for construction as well.
Glacial Ice sheet 2km thick brought Gneiss and Granite boulders down south from the Canadian Sheild.
A large Granite Boulder dropped off by the Glacier. Called an Erratic.
Humans can bring rocks from elsewhere too. This gravel truck mined the rock from a distant location.
Weathering and Erosion
The way the rock looks can tell us what happened to the rock. If the rock is smooth all over and rounded, it tells us that water was involved in smoothing and tumbling the rock. That means its been in a river or lake at some point in its life. If its jagged and rough, that means ice broken it off of a cliff, or humans have mined it at some point in its life. Take a look at the video below for more on weathering and erosion.
Most of these rocks are wind eroded and undercut from a cliff. They are more jagged, but still have somewhat rounded edges. The one on the bottom right is water eroded by the ocean.
This is a rounded piece of Gneiss. It was broken off of a cliff then tumbled along a river where it was found.
This piece came off of a cliff with the freeze thaw of ice. Note the jagged rough edges.
Rock Cycle
The rock cycle and rock type should tell you how the rock was formed. For instance, sedimentary rocks near Toronto were deposited there in the Ordovician era at the bottom of a shallow sea. Intrusive Igneous rocks were born under the surface of the earth from magma, extrusive on top from lava. Use the pictures below to help you find out how your rock was formed and how long ago. Click on the pictures to expand.
Minerals Present
Igneous or Metamorphic rocks:
If darker minerals are present, that usually indicates faster cooling. Faster cooling means that it was at some point perhaps in an ocean fault or closer to the surface (volcano). Lighter coloured minerals mean slower cooling: it was formed deep within the earths surface such as a subduction zone or deep magma chamber.
Sedimentary Rocks:
The grain size will tell you what kind of sediment was there and how fast the current was. Sand indicates faster water. Mudstones and limestones (silt and clay) represent slow water like lakes and oceans with little current. Gravel means much faster water like in rivers or glaciers melting.
