11.1 Folding and Faulting

Factors Affecting Deformation- Temperature & pressure

- Rock type

- Time

- Most crustal deformation occurs along plate margins.

• Deformation - changes in original shape/size of rock body.

This peak is part of the

Karakoram Range in Pakistan.

Types of Stress1. Tensional

2. Compressional

3. Shear

Folds (in sedimentary rock strata) Anticlines - upfolding, or arching (A).

Synclines - linear downfolds (U) found with anticlines.

Monoclines - large step-like folds.

Monocline located near Mexican Hat, Utah.

Anticlines & Synclines

Folding and FaultingAnticline

Syncline

Faults Normal - hanging wall block moves down relative to footwall block.

Reverse - hanging wall block moves up relative to footwall. High angle – dips

greater than 45o (If less than 45o then the fault is called a thrust fault)

Strike-Slip - movement horizontal & parallel to the trend of the fault surface.

Normal Fault - caused the vertical

displacement of these beds located near

Kanab, Utah.

Arrows show the relative motion of

rock units.

RR

R

R

LL

L

L

Fault

1. How does rock folding differ from rock faulting?

2. What makes a reverse fault different from a thrust fault?

3. What is the difference between a hanging wall block and a footwall block?

Use Chapter 11.1 of your textbook to answer the following questions at the end of your notes. Please write out the question in a different color, or you can highlight or underline the question.