So Now!
10 - 7
Expert
BIGGER CRYSTALS means SLOWER COOLING - So Rock "A" Cooled slower
Rock "B" COOLED FASTER because it has SMALLER CRYSTALS
2. Which of these two rocks cooled faster?
Which one cooled slower?
Why do you think that?
5. Why does this rock have holes in it? What guesses can you make about its formation?
The holes are leftover air bubbles.
The rock froze solid before the bubbles could pop and the lava flow back together.
1. These are microscopic pictures
of two different rocks.
Which one had more time to cool & grow crystals?
Rock A had more time to grow crystals.
Crystals always grow BIGGER
when they have MORE TIME to cool.
6 - 4
3. Which of these rocks must have cooled near or on the surface? What did you observe that makes you think that?
Later the rock got pushed closer
to the surface,
causing it to cool much faster
making small crystals.
The rock started off by
cooling slowly
deep underground,
making large crystals.
Magma cools SLOWER underground,
and FASTER on the surface.
So Rock "A" must have cooled UNDERGROUND,
& Rock "B" near the SURFACE.
4. How could this rock have formed both large and small crystals
at the same time?
But then moved closer to
the surface before it finished cooling.
This rock probably began
cooling deep below
the surface.
3 - 0
The crystals are HUGE! NO WAY it cooled fast on the surface!
The HUGE crystlas are telling us that it formed slowly, and
deep underground.
6. Did this rock come pouring out of a volcano as lava? Describe some observations you made
to back up your opinion.
Intermediate
Novice
8. Why are some rocks darker or lighter than others?
Because they're made from different minerals. Duh! :D
7. How can the size of crystals inside an igneous rock tell you how fast that rock cooled, or how deep underground it formed?
Rocks that cool underground cool slower and have larger crystals.
Rocks that cool on the surface cool fast, and have small crystals.
Color?
Crystal Size?
10 What are some characteristcs you would use to group igneous rocks together? How many categories can you make?
THEY MELT!!!!
Hmmmm... What happens to bones and shells that are left in magma at 1000 C?
9. Why can't you seem to find any fossils in these kind of rocks?
Think you can guess
the "Laws" of Igneous Rocks?