Information on Accreted Terrane
suggested grade levels: 9-12/College
view Idaho achievement standards for this lesson
Use the Idaho Digital Atlas. To get there: Click on Atlas Home, mouse-over Geology, then click on Accreted Terrane. Read through the material and click on the links to see the various pictures. Use this information to answer the following questions.
These are links to access the handouts and printable materials.
Accreted Terrane | geo23ho.pdf | geo23AK.pdf
Most of the rock west of the Idaho batholith was formed from oceanic or island arc assemblages. These rocks were accreted to North America between Late-Triassic and Mid-Cretaceous time. This means that before Jurassic time, the West Coast of North America was situated near Riggins, Idaho. Using the Information you have learned, answer the following questions.
1. Look at the map on the main page. Where was the coast of the Pacific Ocean before the Jurassic time period?
2. How has the coast moved from its previous position to its present position?
3. What does the Suture Line represent? What does the strontium isotope ratio have to do with it?
Geology: Geology Topics