1. Translate the following word combinations into Russian:

a soil horizon; physical characteristics; obvious physical features; terms relative to the surrounding material; the result of influences; since the weathering of the soil; the uppermost layers; at a given site; the vertical section exposing; capital letter; fairly universal.

2. Read the following text and say:

a) what the term “soil horizon” means;

b) what subjects are touched upon in the text

Text 4. A soil horizon

A soil horizon is a layer generally parallel to the soil crust, whose physical characteristics differ from the layers above and beneath. Each soil type usually has three or four horizons. Horizons are defined in most cases by obvious physical features, chiefly colour and texture. These may be described both in absolute terms (particle size distribution for texture, for instance) and in terms relative to the surrounding material (i.e., "coarser" or "sandier" than the horizons above and below). The differentiation of the soil into distinct horizons is largely the result of influences, such as air, water, solar radiation and plant material, originating at the soil-atmosphere interface. Since the weathering of the soil occurs first at the surface and works its way down, the uppermost layers have been changed the most, while the deepest layers are most similar to the original parent material.

Identification and description of the horizons present at a given site is the first step in soil classification at higher levels, through the use of systems such as the USDA soil taxonomy or the Australian Soil Classification. The World Reference Base for Soil Resources lists 40 diagnostic horizons. Soil scientists often dig a large hole, called a soil pit (sometimes several meters deep and about a meter wide) to expose soil horizons for study.

The vertical section exposing a set of horizons, from the ground surface to the parent rock, is termed a soil profile. Most soils, especially in temperate climates, conform to a similar general pattern of horizons, often represented as "ideal" soil in diagrams. Each main horizon is denoted by a capital letter, which may then be followed by several alphanumerical modifiers highlighting particular outstanding features of the horizon. While the general O-A-B-C-R sequence seems fairly universal, some variation exists between the classification systems in different parts of the world. In addition, the exact definition of each main horizon may differ slightly.

3. Using the text above, finish the following sentences:

1) A soil horizon … generally parallel to the soil crust, whose physical characteristics differ from the layers above and beneath.

2) Horizons … in most cases by obvious physical features, chiefly colour and texture.

3) These … both in absolute terms (particle size distribution for texture, for instance) and in terms relative to the surrounding material (i.e., "coarser" or "sandier" than the horizons above and below).

4) The differentiation of the soil into distinct horizons … of influences, such as air, water, solar radiation and plant material, originating at the soil-atmosphere interface.

5) Identification and description of the horizons present … is the first step in soil classification at higher levels.

6) The World Reference Base for Soil Resources … diagnostic horizons.

7) Each main horizon … by a capital letter, which may then be followed by several alphanumerical modifiers highlighting particular outstanding features of the horizon.

4. Answer the following questions:

1) What is a soil horizon?

2) Does each soil type usually have horizons?

3) How may soil horizons be described?

4) Is the differentiation of the soil into distinct horizons largely the result of influences and why?

5) What is termed a soil profile? How is denoted each main horizon?

5. Write the summary of the text above.

6. Retell the text “A soil horizon”.

7. Translate from Russian into English:

1) Почвенный горизонт представляет собой слой, обычно параллельный почвенной коре, физические характеристики которой отличаются от слоев, находящихся выше и ниже.

2) Горизонты в большинстве случаев определяются очевидными физическими особенностями, главным образом цветом и текстурой. Они могут быть описаны как в абсолютном выражении (распределением размера частиц для текстуры, например), так и в терминах относительно окружающего материала (т.е. «грубее» или «песчанее», чем горизонты сверху и снизу).

3) Дифференциация почвы на отдельные горизонты в значительной степени является результатом влияния таких факторов, как воздух, вода, солнечная радиация и растительный материал, возникающие на границе раздела грунт-атмосфера.

4) Всемирная база данных по почвенным ресурсам содержит 40 диагностических горизонтов.

5) Каждый главный горизонт обозначается заглавной буквой, за которым затем могут следовать несколько буквенно-цифровых модификаторов, выделяющих особые особенности горизонта.