Section 4: Rocks from Reefs

Structure of calcite (calcium carbonate - CaCO3) skeletons built up by coral animals in warm, shallow ocean water

Most are smaller than your fingernail Tiny algae grow within body and provide

substances that the coral needs to live; coral provides structure to algae

What type of relationship do the coral animal and algae have?

What type of relationship do the coral animal and algae have?

A symbiotic relationship

Coral animal skeletons made when they absorb Ca from water and combine it with C and O to form calcite

When animals die, skeletons remain More corals build on top of them,

gradually forming a reef

How do coral reefs form?

How do coral reefs form? The calcite skeletons of coral animals

remain after the animals die and then more build up on top of them.

Within 40 meters of water’s surface because algae needs sunlight

Warm water of tropical oceans US: Florida & Hawaii Australia – Great Barrier Reef

If sea level rises above a coral reef, what may happen to the reef?

If sea level rises above a coral reef, what may happen to the reef?

If sea level rises slowly, the reef might build upward. If sea level rises too quickly, the reef could die.

Coral reef = organic limestone Limestone deposits that began as reefs

provide evidence of how plate motions have changed Earth’s surface and of past environments Ex. Wherever there were reefs, there were

once a warm climate and shallow ocean water (Midwest & Southwest US)

A geologist finds an area abundant in limestone. What can the geologist infer about that area?

A geologist finds an area abundant in limestone. What can the geologist infer about that area?

S/he can infer that at the time when the limestone formed, the area was in a warm climate and was covered by shallow ocean water.

1. Which element does not make up a coral reef?

a. calciumb. carbonc. borond. oxygen

2. How do coral reefs form?a. coral plants die and their stems

form the reefb. coral animals die and their

skeletons form the reefc. algae hardens and crystallizesd. rock sediment compacts and

cements together

3. Which of the following is not something that corals need to live?

a. deep waterb. sunlightc. algaed. warm water

4. What type of rock does coral reef form?

a. clastic limestoneb. clastic sandstonec. organic sandstoned. organic limestone

5. Remains of a coral reef provide evidence of which of the following?

a. the climate in that area was warm and covered in water

b. the climate in that area was cold and dryc. the climate in that area was cold and

wetd. the climate in that area was warm and

dry