Lesson 2: Grain Size

Question 1

Logarithmic scale for sediment size

Answer 1

Kumbrein Phi Scale

Question 2

Grade scale for expressing particle size that extends from 1/256 mm to >256mm

Answer 2

Udden-Wentworth Scale

Question 3

Size of boulder in Phi (f)

Answer 3

-12.0 - -8.0

Question 4

Size of cobble in Phi (f)

Answer 4

-8.0 - -6.0

Question 5

Size of pebble in Phi (f)

Answer 5

-6.0 - -2.0

Question 6

Size of granule in Phi (f)

Answer 6

-2.0 - -1.0

Question 7

Size of very coarse sand in Phi (f)

Answer 7

-1.0 - 0.0

Question 8

Size of coarse sand in Phi (f)

Answer 8

0.0 - 1.0

Question 9

Size of medium sand in Phi (f)

Answer 9

1.0 - 2.0

Question 10

Size of fine sand in Phi (f)

Answer 10

2.0 - 3.0

Question 11

Size of very fine sand in Phi (f)

Answer 11

3.0 - 4.0

Question 12

Size of coarse silt in Phi (f)

Answer 12

4.0 - 5.0

Question 13

Size of medium silt in Phi (f)

Answer 13

5.0 - 6.0

Question 14

Size of fine silt in Phi (f)

Answer 14

6.0 - 7.0

Question 15

Size of very fine silt in Phi (f)

Answer 15

7.0 - 8.0

Question 16

Size of clay in Phi (f)

Answer 16

8.0 - 14.0

Question 17

What type of method of analysis is used for unconsolidated boulders, cobbles, and pebbles?

Answer 17

manual measurement of individual clasts

Question 18

What type of method of analysis is used for unconsolidated granules and sand?

Answer 18

sieving, settling tube analysis, and image analysis

Question 19

What type of method of analysis is used for unconsolidated silt and clay?

Answer 19

Pipette analysis, sedimentation balances, sedigraph, laser diffractometry, and electro-resistance size analysis

Question 20

What type of method of analysis is used for lithified boulders, cobbles, and pebbles?

Answer 20

manual measurement of individual clasts

Question 21

What type of method of analysis is used for lithified granules and sand?

Answer 21

Thin section measurement and image analysis

Question 22

What type of method of analysis is used for lithified silt and clay?

Answer 22

Electron microscopy

Question 23

Size of very well sorted in Phi

Answer 23

<0.35

Question 24

Size of well sorted in Phi

Answer 24

0.35 - 0.50

Question 25

Size of moderately well sorted in Phi

Answer 25

0.50 - 0.70

Question 26

Size of moderately sorted in Phi

Answer 26

0.70 - 1.00

Question 27

Size of very poorly sorted in Phi

Answer 27

2.00 - 4.00

Question 28

Size of extremely poorly sorted in Phi

Answer 28

> 4.00

Question 29

Grains cut marginally in a thin section have smaller diameters than sieve data. The data is commonly corrected to agree more closely to sieve data.

Answer 29

Corpuscle Effect

Question 30

Analyze and measure grain particles in a thin section

Answer 30

Image Analysis

Question 31

Sediments are slowly poured into an electrolyte solution, where sediments will pass through, where changes in the electrical field will produce pulses, translating into the grain size

Answer 31

Electro-resistance size analyzer

Question 32

Particles that are settling will pass through a diffracted light, and the angle of the diffracted light increases with decreasing particle size. A detector senses the angular distribution of scattered light energy.

Answer 32

Laser Diffraction size analyzer

Question 33

Petrographic microscope fitted with an ocular micrometer, difficulty with this is some randomly oriented sediments may be oriented in the short axis

Answer 33

Thin-section measurement

Question 34

An automated version of thin-section measurement is through _________.

Answer 34

Image processing

Question 35

Interpreting sediment source with these considerations:
• The source of the particles that makes the rocks
• The erosion and transportation mechanisms
• The depositional setting and processes
• Physical and chemical conditions of the burial environment

Answer 35

Provenance Studies

Question 36

Post lithification and diagenesis, sedimentary rocks are used for fingerprinting paleoenvironments

Answer 36

Environmental Studies