How do we know about ancient civilizations?

The ancient cities of Troy and Babylon fell into ruins and the centuries covered them with layers of dirt. Stone pyramids of Central America were deserted and grown over with tangles of jungle. Many an old sailing ship crammed with trading goods, floundered on a reef and preserved its treasures through the centuries under shallow seas.
The detective who investigates ancient civilizations is an archaeologist. He must know many branches of science and be ready to dig or dive for the hidden treasures preserved from the past. First, he must know the likely places in which to look. A certain cave or gorge may have provided a natural shelter for various members of the human family through the ages. Careful digging may reveal old tools and weapons, pottery and perhaps bits of bone.
An aerial picture may show the archaeologist the foundations of an old Roman villa. The site of the old city of Troy was figured out from ancient writings. The hiding places of some of the rained cities of Mexico were traced from legends and rumors. Sponge divers near the shores of Turkey found objects from a graveyard of ancient ships.
When he finds a site the archaeologist gathers a team of skilled workers, for the , fragile treasures must be removed with tender care. He studies a fragment of pottery, a broken hammer or a metal knife and compares it with other items in his wide experience. Copper ingots found in an old ship wreck, for example, were shown in ancient Egyptian pictures.
Through the ages, there have been changing fashions in pottery, carving, writing, metal work and the making of tools and weapons.
The archaeologist can often tell from ascrap of pottery who made it and more or less when it was made, This helps him date his site. For more exact dating, he may send materials to special laboratories. A test with carbon 14 can tell the age of a wooden carving as old as 50,000 years. The newer potassium argon test can date objects millions of years old.
The archaeologist sifts, sorts and compares countless items to get a total picture of an ancient culture. Man made objects tell him the skills a civilization had developed. Bit by bit the picture unfolds and he learns how these ancient people went about the details of their daily lives.
The ruined cities of Mexico revealed the building, carving and other skills of the ancient Mayans and showed that they had developed the most advanced number system of their time. Salvage from a 3,300 year old shipwreck off the Turkish coast shed new light on the Bronze Age of history.