Lecture 12

Question 1

What are deltas?

Answer 1

A prism of sediment that forms where a river enters a marine environments
- mixture of marine and fluvial influences and a reconstructive

Question 2

What causes river to quickly drop its sediment load to contribute to the formation of a delta?

Answer 2

abrupt decrease in energy

Question 3

What happens to sediments as you move farther into the lake or ocean?

Answer 3

become finer

Question 4

What are the 3 main sub environments of deltas?

Answer 4

1) delta plain
2) delta front
3) pro delta – seaward extent of delta influence

Question 5

What is the active lobe of a delta?

Answer 5

• growing potion of delta

- switches lobes in the past

Question 6

What is the abandoned lobe of a delta?

Answer 6

• sediments compact
• love sinks
• new lobe forms on top

Question 7

What is an estuary?

Answer 7

Seaward portion of a drown valley system which is influenced by both marine and fluvial processes

Question 8

What produces an estuary?

Answer 8

transgression

Question 9

What type of water environment is an estuary?

Answer 9

brackish

Question 10

What is the tripartite division of an estuary?

Answer 10

• bay head delta - sand
• central lagoon/basin - mud
• barrier island - sand

Question 11

What are organic reefs?

Answer 11

Sedimentary features built by the interaction of calcium carbonate secreting organisms in response to their environment

Question 12

Where are organic reefs common?

Answer 12

shallow, tropical waters where siliciclastic sediments are rare

Question 13

What is a prominent feature in nearshore environments, and in the geological record form fossiliferous limestones?

Answer 13

reefs

Question 14

What are modern reefs formed from?

Answer 14

coral

Question 15

What are ancient reefs formed from?

Answer 15

different organisms

Question 16

What is talus?

Answer 16

Broken reef rock on seaward side

Question 17

What is front reef?

Answer 17

durable structures

Question 18

What is reef flat?

Answer 18

grows too almost low sea level (within a meter or so)

Question 19

What is back reef?

Answer 19

Often with more ornate structures

Question 20

What are the 2 parts to reef-lagoon complexes (has to do with zones, formation time,and calcium carbonate)?

Answer 20

1. photic zone (most modern reefs were formed in the last 10 000 years)
2. calcium carbonate is most readily dissolved and precipitated in warm water

Question 21

True of False: Different organisms through geological time have been responsible for reef building.

Answer 21

True

Question 22

What are 4 examples of organisms that have been responsible for reef building through geological time?

Answer 22

• stromatolites - cyanobacteria
• sponges
• tabulata and rugosa corals
• bivalve - rudists

Question 23

What is the fair-weather wave base depth?

Answer 23

depth beneath the average daily waves

Question 24

What is the storm weather wave base depth?

Answer 24

depth beneath storm driven waves

Question 25

What des reposition of storm deposits called temestite result from?

Answer 25

stormweather wave base

Question 26

What is turbidite (what does it produce, and how is it sorted)?

Answer 26

• produces graded deposit due to gravity flows

- poorly sorted coarse grains at base and fine grains at tope

Question 27

What are pelagic sediments?

Answer 27

Fine-grained sediments that accumulate by settling through the water column.