Bearing is the expression of direction using degree of an angle. the following are procedure to be followed when determining position of the place by bearing and distance when you asked to determine a position of A from B
Obtain the map needed
Consider the points A and B and identify the distance needed
Measure the distance between the two places and convert it into ground distance. for example given the FR scale is 1:50000, and the map distance obtained is 9cm therefore actual ground distance will be 4.5km
Give the position by distance i.e B is situated 4.5km from A
Give the position by bearing follow these procedures
Join the two places by straight line
Draw the four major points of the compass at the place of reference i.e point A
Using protractor measure the angle (from north) clockwise until you get to the line joining A and B
Give the position by bearing e.g point B bear at 95 degrees east from A
Give the overall position, that is point B bears at 4.5km point a. 95 degrees East.
Statement scale is the type of map scale expression in which scale is expressed in form of a written statement, for example, one centimeter on the map represents ten kilometers on the ground. This can also be expressed in short as 1cm represent 10km or 1cm to 10km.
The following are features of statement scale;
The scale is expressed as a word statement.
The scales bear specific units of measurement. The unit of measurement used in the map is smaller than the actual measurements on the ground, for example, 1cm represents 10km
The word ”represent” should be used. do not use ”equivalent” or ”equal”. For example, do not say one centimeter on the map is equal to ten kilometers on the ground. This is because the statement is not true. instead, say one centimeter on the map represents ten kilometers on the ground.
The map distance always carries the digit 1 while that of the ground may be less than 1, 1, or more than one.
A statement scale is simple to express. However, it may be difficult for users who are not familiar with the unit of measurement used in the scale. If the map is used or enlarged, the scale will not remain the same
Research may be defined as the systematic and objective analysis and recording of controlled observation that may lead to the development of generalizations, principles, or theories, resulting in prediction and possibly ultimate control of an event.
The following are two types of research:
Basic research is the kind of research conducted with the aim of generating and expanding knowledge. It includes the generalization and formulation of principles or theories.
The fundamental research is sometimes carried on in a laboratory or other sterile environment, sometimes with animals.
This type of research has no immediate or planned applications, may later result in further research of an applied nature.
Characteristics of basic research are:
It is conducted in a specific area for example in the laboratory.
It takes a long time to conduct as it involves the investigation of a particular problem.
There are three types of plate boundary (or margin): constructive, destructive and passive.
These arise where two plates move away from each other, and new crust is created at the boundary. They are mainly found between oceanic plates, and are consequently underwater features.
Rift valleys may initially develop, but molten rock from the mantle (magma) rises to fill any possible gaps. Constructive margins are often marked by ocean ridges (e.g. the Mid-Atlantic Ridge, the East Pacific Rise).
The rising magma forms submarine volcanoes, which in time may grow above sea level (e.g. Iceland, Tristan da Cunha and Ascension Island on the Mid Atlantic Ridge, and Easter Island on the East Pacific Rise).
Different rates of latitudinal movement along the boundary cause transform faults to develop as the magma cools – these lie perpendicular (at a right angle) to the plate boundary.
Of the annual volume of lava ejected onto the Earth’s surface, 73 per cent is found on mid-ocean ridges, and approximately one-third of the lava ejected onto the Earth’s surface during the past 500 years is found in Iceland.
The Atlantic Ocean formed as the continent of Laurasia split in two, and the Atlantic is continuing to widen by approximately 2–5 cm per year. Very rarely, constructive margins can occur on land, and it is thought that this is happening inEast Africa at the Great African Rift Valley System.
Extending for 4,000 km from the Red Sea to Mozambique, its width varies from 10 to 50 km, and at points its sides reach over 600 m in height.
Where the land has dropped sufficiently, the sea has invaded. – it has been suggested that the Red Sea is the beginnings of a newly forming ocean. Associated volcanoes include Mount Kilimanjaro and Mount Kenya to the east and Ruwenzori to the west.
These occur where two plates move towards each other, and one is forced below the other into the mantle.
The Pacific Ocean is virtually surrounded by destructive plate margins with their associated features, and its perimeter has become known as the Pacific Ring of Fire.
The features present at destructive margins will depend upon what types of plates are converging.
When oceanic crust meets continental crust:
The thinner, denser oceanic crust is forced to dip downwards at an angle and sink into the subduction zone beneath the thicker, lighter and more buoyant continental crust.
A deep-sea trench forms at the plate margin as subduction takes place. These form the deepest areas on the planet.
As the oceanic crust descends, the edge of the continental crust may crumple to form fold mountains, which run in chains parallel to the boundary (e.g. the Andes).
Sediments collecting in the deep-sea trench may also be pushed up to form fold mountains.
As the oceanic crust descends into the hot mantle, the additional heat generated by friction helps the plate to melt, usually at a depth of 400–600 km below the surface.
As it is less dense than the mantle, the newly forme magma will tend to rise to the Earth’s surface, where it may form volcanoes.
However, as the rising magma at destructive margins is very acidic, it may solidify before it reaches the surface and form a batholith at the base of the mountain chain .
As the oceanic plate descends, shallow earthquakes occur where the crust is stretched as it dips beneath the surface. Deeper earthquakes arise from increases in friction and pressure may be released as earthquakes.
The area in the subduction zone where most earthquakes take place is known as the Benioff zone.
The depth of the deeper earthquakes may also provide an indication as to the angle of subduction, where gentler angles of subduction give rise to shallower earthquakes.
If subduction occurs offshore, island arcs may form (e.g. Japan, the West Indies).
When oceanic crust meets oceanic crust:
Where two oceanic plates collide, either one may be subducted.
Similar features arise as those where an oceanic plate meets a continental plate.
When continental crust meets continental crust (note that this is very rare):
Because continental crust cannot sink, the edges of the two plates and the intervening sediments are crumpled to form very deep-rooted fold mountains.
The zone marking the boundary of the two colliding plates is known as the suture line.
These boundaries mark the site at which the Earth’s crust is at its thickest. For example, the Indo-Australian Plate is moving northeastwards and is crashing into the rigid Eurasian Plate, creating the Himalayas.
Uplift is a continuous process (it is happening right now); however, weathering and erosion of the mountain tops means that the actual height of the mountains is not as great as the rate of uplift would suggest.
Sediments which form part of the Himalayas were once underlying the Tethys Sea, which existed at the time of the Pangean supercontinent.
These occur where two plates slide past each other and crust is neither created nor destroyed.
The boundary between the two plates is characterized by pronounced transform faults, which lie parallel to the plate boundary.
As the plates slide past each other, friction builds up and causes the plates to stick, and release is in the form of earthquakes.
An excellent example of a passive margin is the San Andreas Fault (one of several hundred known faults) in California, which marks a junction between the North American and the Pacific Plates.
Although both plates are moving in a northwesterly direction, the Pacific Plate moves at a faster rate than the North American late (6 cm per year, compared with just 1 cm per year), creating the illusion that the plates are moving in opposite directions.
The Earth’s lithosphere (crust and upper mantle) is divided into seven large and several smaller plates.
These plates are constantly moving, and are driven by convection currents in the mantle.
Plate boundaries mark the sites of the world’s major landforms, and they are also areas where mountain-building, volcanoes, and earthquakes can be found.
However, in order to account for such activity at the plate boundaries, several points should be noted
Continental crust is less dense than oceanic crust so it does not sink.
Whereas oceanic crust is continuously being created and destroyed, continental crust is permanent, and hosts the oldest rocks on the planet (the shieldlands).
Continental plates may be composed of both continental and oceanic crust (e.g. Eurasia).
Continental crust may extend further than the margins of the land masses (when continental crust is covered by an ocean, it is known as continental shelf).
It is not possible for plates to overlap, so they may either crumple up to form mountain chains, or one plate must sink below the other.
If two plates are moving apart, new crust is formed in the intervening space, as no ‘gaps’ may occur in the Earth’s crust.
The earth is not expanding, so if newer crust is being created in one area, older crust must be being destroyed elsewhere.
Plate movements are geologically fast and continuous. Sudden movements manifest themselves as earthquakes.
Very little structural change takes place in the centre of the plates (the shield lands). Plate margins mark the sites of the most significant landforms, including volcanoes, batholith intrusions, fold mountains, island arcs and deep-sea trenches
Statistics being the scientific and systematic methods dealing with numerical facts is broadly categorized into two types depending on how data is handled.
The two main categories of statistics are descriptive and inferential statistics.
this deals with recording, summarizing, analyzing and presentation of numerical facts that have been actually collected.
Descriptive statistics is the term given to the analysis of data that helps describe, show or summarize data in a meaningful way such that, for example, patterns might emerge from the data.
Descriptive statistics do not, however, allow us to make conclusions beyond the data we have analyzed or reach conclusions regarding any hypotheses we might have made.
They are simply a way to describe our data. Descriptive statistics are very important because if we simply presented our raw data it would be hard to visualize what the data was showing, especially if there was a lot of it.
Descriptive statistics, therefore, enables us to present the data in a more meaningful way, which allows a simpler interpretation of the data.
For example, if we had the results of 100 pieces of students’ coursework, we may be interested in the overall performance of those students.
We would also be interested in the distribution or spread of the marks. Descriptive statistics allow us to do this.
Typically, there are two general types of statistics that are used to describe data they are a measure of central tendency and measure of spread
this makes inferences about populations using data drawn from the population.
Instead of using the entire population to gather the data, the statistician will collect a sample or samples from the millions of residents and make inferences about the entire population using the sample.
With inferential statistics, you are trying to reach conclusions that extend beyond the immediate data alone.
For instance, we use inferential statistics to try to infer from the sample data what the population might think.
Or, we use inferential statistics to make judgments of the probability that an observed difference between groups is a dependable one or one that might have happened by chance in this study.
Thus, we use inferential statistics to make inferences from our data to more general conditions; we use descriptive statistics simply to describe what’s going on in our data.
The vertical aerial photograph is an aerial photograph technique where the shots are taken from directly above the subject of the image.
Hence, this method of aerial photograph is also often referred to as “overhead aerial photograph.
Oblique photographs (also known as oblique aerial photographs or oblique air photographs) are taken from a high point, which is at an angle neither horizontal (ground level photograph) nor perpendicular (vertical aerial photograph) to the area being photographed.
The following are advantages of vertical aerial photograph over oblique aerial photograph;
vertical aerial photograph have uniform scale
Vertical photographs present approximately uniform scale throughout the photo but not oblique photos. It follows that making measurements (e.g., distances and directions) on vertical photographs is easier and more accurate.
it is easy to determine direction in vertical aerial photograph
Because of a constant scale throughout a vertical photograph, the determination of directions (i.e., bearing or azimuth) can be performed in the same manner as a map. This is not true for an oblique photo because of the distortions.
vertical aerial photograph are easier to interpret
Because of a constant scale, vertical photographs are easier to interpret than oblique photographs. Furthermore, tall objects (e.g., buildings, trees, hills, etc.) will not mask other objects as much as they would on oblique photos.
vertical aerial photograph are easier to use
Vertical photographs are simple to use photogrammetrically as a minimum of mathematical correction is required.
vertical aerial photograph can be used as maps
To some extent and under certain conditions (e.g., flat terrain), a vertical aerial photograph may be used as a map if a coordinate grid system and legend information are added.
vertical aerial photograph can be used for stereoscopic study
The stereoscopic study is also more effective on vertical than on oblique photographs.