Joints and Fractures

Question 1

Joints with patterns that are typically arranged in roughly hexagonal arrays that isolate columns of rock formed during the cooling of igneous rocks

Answer 1

Columnar Joints

Question 2

Unfilled or filled joints that come in pair

Answer 2

Conjugate Joints

Question 3

Through-going joints in continuous joints

Answer 3

Master Joints

Question 4

Joints that do not share a common orientation and those with highly curved and irregular fracture surfaces

Answer 4

Nonsystematic Joints

Question 5

Through-going joints that can be traced across an outcrop

Answer 5

Continuous Joints

Question 6

Short joints that occur between the continuous joints

Answer 6

Cross Joints

Question 7

Joints which trend at high angles (~60 to 90 degrees) to the regional bedding strike

Answer 7

Cross-strike Joints

Question 8

Joints formed in a layer of mud when it dries and shrinks into roughly hexagonal plates

Answer 8

Desiccation Cracks

Question 9

Short joints that terminate within an outcrop, generally at the intersection with another joint

Answer 9

Discontinuous Joints

Question 10

Set of joints that roughly parallels ground surface topography and whose spacing decreases progressively toward the surface

Answer 10

Exfoliation Joints

Question 11

Pre-existing microcracks and flaws in a rock, which include grain-scale fractures, pores and grain boundaries

Answer 11

Griffith Cracks

Question 12

Joints that form at depth in response to abnormal fluid pressure and involving hydrofracturing

Answer 12

Hydraulic Joints

Question 13

Joints that share a similar orientation in the same area

Answer 13

Joint Set

Question 14

Two or more joint set in the same area

Answer 14

Joint System

Question 15

Joints that merge with the fault and are inclined at an angle around 30 to 40 degrees to the fault surface

Answer 15

Pinnate joints

Question 16

Joints that exhibit feathered structure

Answer 16

Plumose Joints

Question 17

Joints that form late in history of an area and are ultimately oriented perpendicular to the original tectonic compression that formed from the dominant fabric in the rock

Answer 17

Release Joints

Question 18

Joints which parallel the general strike of bedding

Answer 18

Strike-parallel Joints

Question 19

Joints that have subparallel orientation and regular spacing

Answer 19

Systematic Joints

Question 20

Joints that form at depth (<3km) with stress originating tectonically and horizontal compaction occurs

Answer 20

Tectonic joints

Question 21

Joints that form because of the lack of shear involved

Answer 21

Tensile fractures

Question 22

Joints that form when more than half of the original overburden have been removed from a rock mass

Answer 22

Unloading Joints

Question 23

Joints filled with minerals or aggregates

Answer 23

Veins

Question 24

New tensile cracks that spawn from propagating shear-mode cracks

Answer 24

Wing cracks