May 30
2019
Geologic Time Scale & Changes to Continents
Hello friends,
The 7th graders are learning about Plate Tectonics right now, which is our explanation for how the continents moved around the surface of the Earth over time. This relates a lot to Geologic Time which we have been talking about for a few weeks! I mentioned a lot about the conditions on Earth in each time period but I found this video that really gives a great representation for you to check out.
- It, like the Earth, starts in PreCambrian time. You can see that most of the Earth is water / oceans at this point.
- Slowly land masses start to form. Some disappear, some stay.
- By 2 billion years ago (25 sec into the video), some of our current continents have started to form…
- At first, all you see right is their cratons — the parts of the continent that have been around the longest.
- As the colorful pieces of land start to combine (at convergent boundaries of their original tectonic plates), the cratons start to build up the large continents we have today.
- Divergent boundaries between land masses move them apart from each other.