Word formation

fold (n) – folding (n)	складка – складкообразование;
curve (n) – curvature (n)	кривая – кривизна;
associate (v) – association (n)	ассоциировать – ассоциация.

VERBS (+ PREPOSITION)

to drape over – ниспадать складками;

to precede – предшествовать;

to manifest – проявляться, становиться явным;

adjacent to – смежный, расположенный рядом;

to converge upon – стремиться к пределу;

to associate with – связывать с, ассоциировать с.

0. Fold terminology (r.P. - 8.3.2.1, 8.3.2.3)

Folding in layered rocks consists of deformation of strata without faulting. Folds are formed by compression, draping over basement blocks, and compaction. Faulting often accompanies folding and can precede it or follow it. The triaxial stress system for folding is representative for faulting since the two are intimately related.

Folds are manifested as different types according to morphology, origin and type of internal deformation. General fold terminology is descriptive and relates to elements of individual features applicable to all types of folds

1. Anticline is a fold with upward convexity. Beds that make up an anticline dip in opposite directions away from the crest or high point of the fold.

1. Syncline is a concave upward. Beds making up a syncline dip in opposite directions toward the trough, or low point of the fold.

3. The hinge point occurs at the locus of maximum curvature of a fold. The hinge point is applicable equally to anticlines and synclines. Hinge points connected on any particular bedding surface are joined along a hinge line.

4. The locus of all hinge lines of a fold is the hinge surface of the fold.

5. An inflection point occurs where bed curvature in one direction changes to bed curvature in the opposite direction. Inflection occurs where concavity changes to convexity.

6. The limbs or flanks of folds are those portions adjacent to the inflection lines of folds. They converge upon the inflection line synclines and diverge from it in anticlines.

7. A fold is symmetrical when its shape and mirror image are identical or when the fold is bilaterally symmetrical about the hinge surface. Symmetrical folds are usually represented by a vertical hinge surface.

8. A fold that is not bilaterally symmetrical about the hinge surface is asymmetrical. Its hinge surface is usually inclined.

(Абрамова Р.Н., Квеско Н.Г., Introduction to Continuum Mechanics- учебное пособие, Томск, ТПУ. 2005.)

Fig. 53. Fold terminology

Fig. 54. Folding structure

3.2.3 EXERCISES

1. Take a piece of paper. Fold it like a fan. What does it look like? Does it show the geometric parts of a fold?

2. Read the definitions and draw the corresponding folds and label them. (R.P 8.3.2.2)

1. Rock beds are folded into an arch;

arch from a few feet to many miles across;

2. Downfolded sedimentary rock layers that

form a basin. Immense synclines are called

geosynclines.

3. Its shape and mirror image are identical; a vertical

hinge surface.

4. Hinge surface is usually inclined.

5. Both limbs and the axial plane dip in the same direction

3.2.4 LISTENING COMPREHENSION

You will hear part of a lecture. For statements 1- 8, complete the notes, which summarize what the speaker says. You will need to write a word or short phrase in each box.

1. Sediments accumulate horizontals beds or ____________________.

2. The old deposits can be usually found in _______________________.

3. The main forces that form mountains are tilting, breaking __________ and ________________.

4. These forces are affected by _______________ and ______________.

5. Each type of deformation depends on two factors: ____________ and ______________.

6. Folding occurs at the edges of _______________ _____________ ____________.

7. High temperature and pressure ______________ brittle rocks.

8. There are ________________ types of folds.