- •Analysis (introduction)
- •I. Структура предложения
- •II. Явные сказуемые
- •III. Неявные сказуемые
- •1) Present Indefinite
- •2) Past Indefinite
- •Part I section 1 geology
- •Exercises
- •Word-Building
- •Grammar Exercises
- •Lexical Exercises
- •Analysis
- •Section 2 geology
- •Exercises
- •Word-Building
- •Word Study
- •Grammar Exercises
- •Lexical Exercises
- •Analysis
- •Section 3 historical geology
- •Exercises Word-Building
- •Word Study
- •Grammar Exercises
- •Analysis
- •Section 4 the earth and the solar system
- •Exercises
- •Word-Building
- •Grammar Exercises
- •Word Study
- •Lexical Exercises
- •Analysis
- •Section 5 the solar system
- •Exercises
- •Word-Building
- •Word Study
- •Grammar Exercises
- •Lexical Exercises
- •Analysis
- •Section 6 the great parts of the earth
- •Exercises
- •Word-Building
- •Word Study
- •Grammar Exercises
- •Lexical Exercises
- •Section 7 the earth's crust, rocks, minerals
- •Exercises
- •Word-Building
- •Grammar Exercises
- •Word Study
- •Lexical Exercises
- •Section 8 (revision of sections 1-7)
- •Supplementary texts and extracts (for reading, discussion, translation, analysis)
- •I. Geology (introduction)
- •II. Mineralogy in russia
- •III. Mineralogy and geochemistry in the ussr
- •V. I. Vernadsky (1863 - 1945)
- •A. E. Fersman (1883 - 1945)
- •IV. Our place in the universe
- •V. Soviet scientists study earth's weather and the sun
- •VI. The lithosphere
- •VII. Environments
- •VIII. Igneous rocks
- •IX. The occurrence of minerals
- •X. Sedimentary rocks
- •XI. Laws of sedimentary sequence
XI. Laws of sedimentary sequence
Observations of strata now accumulating make possible the following ge-neralization, which, though rather obvious, are nevertheless useful in interpre-ting ancient sedimentary rock. The first is the law of original horizontality: Water-laid sediments are deposited in strata that are almost horizontal, and para-llel or nearly parallel to the surface on which they are accumulating.
This law was first clearly stated in 1669 by Nicolaus Steno. It applies to all sediments deposited in water except certain small accumulations, such as sandbars, in which, as in dunes of windblown sand, some strata may be laid down at a marked angle to the other strata within the same deposit.
The second is the law of superposition: In any pile of sedimentary strata that has not been disturbed by folding or overturning since accumulation, the youngest stratum is at the top and the oldest at the base. In other words, the order of deposition is from the bottom upward.
A simple structure like the stratification of a sediment thus helps us to read the record of great changes in the earth's crust - changes that have bent and broken once horizontal sheets of rock into fantastically complex patterns.