-Characteristics of Igneous Rocks-
(i)They are crystalline in structure i.e. they contain crystals.
(ii)They do not occur in layers i.e. they are non-stratified rocks.
(iii)They do not contain fossils.
(iv)They are usually hard and impervious.
-Mode of Formation of Igneous Rocks-
They are formed by the cooling and solidification of molten rocks called magma, ejected from beneath the earth’s crust. The magma which results from high temperature and pressure beneath the earth, forces itself towards the earth’s surface through cracks. As the magma moves towards the surface, it comes in contact with lower temperature, hence it cools and solidifies to form igneous rocks.
(i)They are used as sources of fuel for domestic and industrial uses.
(ii)Some beautiful rocks such as marble can be polished as ornaments for decorating floors, walls of buildings, etc.
(iii)Soils are formed from disintegration of rocks.
(iv)They are sources if metals which are derived from mines e.g. gold, silver, copper, etc.
(i)Structural Plains : These are relatively undisturbed horizontal surfaces of the earth, formed by bedded sedimentary rocks. Examples include the Russian platform and the Great Plains of the USA.
(ii)Erosional Plains : These plains are formed by the agents of denudations such as rivers, wind, rain, glacier and ocean waves which wear out irregular rock surfaces and smoothen then into plains know as erosion plains.
Weather is the condition if the atmosphere of a place at a certain time over a shirt period; while Climate is the average atmospheric conditions of an area over a long period of time.
(i)Slope and aspect: slope experiences more rapid change in temperature than a gentle slope.
(ii)Cloud Cover : Cloud reduces the amount of solar radiation reaching the earth’s surface and the amount of solar radiation escaping from the earth surface into space.
(iii)Natural Vegetation and soil: The thick foliage (leaves) of heavy forest cuts off much of the incoming sunlight energy. As a result, the forest temperature is cool and lower than that of the open ground (soil).
(iv)Latitude : This refers to the location of a place on the earth’s surface in relation to the equator. Tropical latitudes, where the sun’s altitude is always high have hotter temperature than lower latitudes where the sun’s altitude is generally low.
(i) Tropical zone: from 0°–23.5°(between the tropics)
In the regions between the equator and the tropics (equatorial region), the solar radiation reaches the ground nearly vertically at noontime during almost the entire year.
(ii)Subtropics: from 23.5°–40° The subtropics receive the highest radiation in summer, since the Sun’s angle at noon is almost vertical to the Earth, whilst the cloud cover is relatively thin.
(iii)Temperate zone: from 40°–60° In the temperate zone, the solar radiation arrives with a smaller angle, and the average temperatures here are much cooler than in the subtropics.
(iv)Cold zone: from 60°–90°
The polar areas between 60° latitude and the poles receive less heat through solar radiation, since the Sun has a very flat angle toward the ground.
Environmental resources are useful things (both living and non-living) occurring naturally within a particular geographical location which are benefit to man, animals and plants.
(i)Poor technological know-how, such as storage.
(ii)Inadequate capital i.e. high cost of harnessing it.
(iii)Unreliability e.g. periods when the sun is not overhead.
(i)The increase in ultra-violet rays increases the amount of solar radiation on the earth’s surface.
(ii)Excessive ultra-violet rays leads to increase in skin cancer in man.
(iii)Possible increase in precipitation.