Facies

Question 1

facies

Answer 1

Includes all the characteristics of a sedimentary rock that are produced by its environment of deposition and allow it to be distinguished from rock deposited in an adjacent environment.

Question 2

lithofacies

Answer 2

include all the physical and chemical characteristics of a rock

Question 3

biofacies

Answer 3

include the palaeontological characteristics of a rock

Question 4

facies association

Answer 4

describes a group of sedimentary facies that occur together and typically represent one depositional environment

Question 5

what characteristics are used to distinguish rocks from each other? x5

Answer 5

mineral content, grain size, sorting, structures, fossil content etc.

Question 6

how can ancient glacial deposits be recognised? x4

Answer 6

striations, tillites, varves, fluvio-glacial sand and gravels

Question 7

littoral zone

Answer 7

the area between the extreme low and extreme high water of the spring tides

Question 8

polymictic conglomerate

Answer 8

a coarse grained sedimentary rock containing clasts of many different rock types

Question 9

oligomictic conglomerate

Answer 9

a coarse grained sedimentary rock containing clasts of few different rock types

Question 10

monomictic conglomerate

Answer 10

a coarse grained sedimentary rocks containing clasts from a single rock type

Question 11

what is the most important process in fluvial transport?

Answer 11

Sorting by size. Coarser grains are deposited near river source, sand size grains- middle course, finer grained- near mouth.

Question 12

what is the maturity of river transported sediments?

Answer 12

sub-mature

Question 13

where do deposits in shallow marine environments occur?

Answer 13

littoral zone and continental shelf

Question 14

how are littoral deposits sorted?

Answer 14

opposite to rivers. coarser grains are transported greater distances

Question 15

How is weathering important to shallow marine transport?

Answer 15

grains must be able to withstand high-energy waves

Question 16

till fabric analysis

Answer 16

a method of tracing the former movement direction of ice by taking compass bearings on the long axes of large clasts in till deposits

Question 17

fluvial -glacial deposit

Answer 17

sediments produced by meltwater streams flowing from a glacier

Question 18

Describe the properties of sedimentary rocks transported by glaciers

Answer 18

very poorly sorted
fine matrix of non-resistant roc
coarser pebble and cobble are more resistant

Question 19

what is the name for sediments transported by glaciers?

Answer 19

till

lithified= tillites

Question 20

what does till fabric analysis show?

Answer 20

boulders within till tend to lie with their long axes parallel to the direction of movement of the ice.

Question 21

what is the most common mineral transported by wind|?

Answer 21

quartz

Question 22

why are sediments transported by wind texturally and mineralogically mature?

Answer 22

limited size range and grains resistant to mechanical weathering

Question 23

Banded Iron Formations (BIFs)

Answer 23

Units of sedimentary rock of Precambrian age consisting of alternating layers of iron oxide and chert

Question 24

why do streams migrate across flood plains?

Answer 24

Bank undercutting on one side of meander and deposition of point bar deposits on the other side. in-between are channel deposits

Question 25

What happens to shallow siliciclastic seas and beaches during marine transgression ad regression?

Answer 25

they migrate laterally along the coast

Question 26

Walter’s law

Answer 26

to be conformable, vertically adjacent facies must reflect those environments which occur side by side.

Question 27

How do BIFs form?

Answer 27

photosynthetic bacteria oxidise ferrous iron into ferric iron using sunlight. Chert bands deposited by silica-forming organisms. rhythmic nature of deposition suggest cyclic variation in conditions.