Earthquakes on the ocean floor can give a tremendous push to surroundings seawater and create  one or more large, destructive waves called tsunamis, also known as seismic sea waves. Some people ca...

DNA (short for deoxyribonucleic acid) is the basic unit of control of human life. It is a highly complex substance formed from a chain of chemical units called nucleotides. All the the instructions for growing a...

There is more than one gene for eye pigment, as shown in the illustration below, but brown is always dominant over blue. Two people, one with two genes for brown eyes, the other with two  genes for blue...

People are rapidly destroying the world's rain forests. In 1950, rain forests covered about 8,700,000 square miles (22,533,000 square km) of the earth. This area would cover about three-quarters of Africa. Today,...

From a hazy mixture of history and legend, we learn that China's first ruling family was the Hsia. The legendary first emperors are said to have tamed the rivers, so that farmers could grow millet and wheat. The...

In the AD 500s, an Italian named Benedict of  Nursia drew up a set of rules for monks (or people in monasteries). All monks must be poor, unmarried and obedient. Monks wore simple robes, shaved their...

The most powerful ruler among the English kings was acknowledged as 'bretwalda', or supreme king. The Sutton Hoo ship burial site in Suffolk was discovered in AD 1939. It is almost certainly the monument to...

Rome grew from a small kingdom in Italy. It became a republic and one of the mightiest empires of the ancient world, with an empire stretching the length of the Mediterranean Sea. At its peak, the Roman Empire...

Egyptian picture-writing is known as  HIEROGLYPHICS. This language is made up of about 750 signs, with pictures of people, animals and objects. until hieroglyphics was deciphered in modern times, it was not known that most of the picture represented sounds and syllables,...

More than 5,000 years ago Europeans were building spectacular stone monuments. Many of these are still standing today, as mysterious relics of a long-gone society. The huge stones that were used are called megaliths...

Climate is what the weather pattern is like over  a long time. The seasonal pattern of hot and cold, wet or dry, is averaged over 30 years. The climate is different around the world as it is not heated evenly by the...

WHAT SHAPES THE COASTS? Coastlines are constantly changing: they are either being eroded or built up. The waves are very powerful and can remove a large amount of material from a coastline, specially during a storm. The sand and pebbles removed from the coastline are carried...

River start on the top of hills as small streams channelling  the rainfall or as a spring releasing ground water. They begin to cut at and change the landscape on the way to the sea. In the highlands the water can move...

Over 10,000 years ago about a third of the land surface was covered by ice. Today a tenth is still covered in ice. Ice sheets can cover very large areas and can be very thick. The world's largest ice sheet covers most of &nbs...

Glacier begin to from when more snow falls during the winter than melts and evaporates in summer. The excess snow gradually builds up in layer. its increasing weight causes the snow crystals under the surface to...

A desert landscape includes various kinds of surface features created by water and air erosion and by deposits of silt, sand, and other sediments. The drainage system is made up of normally dry streams called arroyos. After a rainfall, water fills the stream channels called wadi  1....

Erosion is the natural process by which rock are broken loose from the Earth,s surface at one location and moved to another. Erosion changes land by wearing down mountains, filling in valleys, and making rivers...

The continental margins forms the part of the seabed that borders the continents. It consist of (1) the continental sheft, (2) the continental slope, and (3) the continental rise.  The continental shelf is submerged...

The bottom of the ocean has feature has varied as those on land. Huge plains spread out across the ocean floor, and long mountain chains rise toward the surface. Volcanoes erupt from ocean bottom, and deep...

Plate tectonics is a theory that explains the origin of most of the major features of the Earth's surface. For example, the theory tells us why most volcanoes occur where they do, why there are high ridges and deep trenches in the oceans, and how mountains form. According to this...

WHAT DID THE CONTINENTS USED TO LOOK LIKE? When the Earth formed, the lighter elements floated to the surface where they cooled to form a crust. Although the first rock were formed over 3,500 years ago they have not stayed the same. They have been changed from forces on the...

WHAT ARE OCEAN TRENCHES? Trenches are the deepest parts of the ocean. Many renches occur in the Pacific Ocean, especialy its in wesstern portion. Most trenches are long, narrow, and deep, 2 to 2.5 miles (3 to 4 km) below the the surrounding sea floor. The greaest depth anywhere in the...

WHAT DEFINES A DAY? For early peoples, the only changes that were truly regular, were the motion of the objects in the sky. The obvious of these changes was the alternate daylight and darkness, caused by the rising  and setting of the sun. Each of these cycles of the sun came...

WHAT IS THE DEPTH OF THE PACIFIC OCEAN? The pacific ocean, the largest and deepest of the world's four oceans, covers more than a third of the earth's surface and contains more than half of its free water. The floor of the pacific ocean, Which has an average depth of around 14,000...

WHAT CAUSES TIDES?OUR WORLD? Tides are the periodic rise and fall of all oceans,  caused by the gravitational pull of the Moon. The moon's pull on the earth draws the ocean water towards the Moon,  making the water form a huge swell. This is known as a high tide. Water...

WHAT ARE MOLLUSCS?  After insects, molluscs form the largest group of animals. Molluscs have soft, muscular bodies, often covered by a protective shell. Some, such as snails, move on a muscular foot , which can be withdrawn into the shell for protection. Other, sea-dwelling...

WHAT IS INSIDE THE STOMACH? If you did not have a stomach you could not eat just two or three main mails each day. You would have to eat lots of tiny ones much more frequently. The stomach is like a stretchy storage bag for food. It expands to hold a whole meal. Then the layer...

 Everything you eat has to be chopped up the broken before the nutrients or goodness in it can be taken into your blood and used by your body cell to make energy. This chopping up and breaking down takes place in your digestive system, or gut. Digestion begins with the...