What is Archaeology?
In a nutshell, Archaeology is the science of finding and examining the things (artifacts or artefacts) which we find there and concluding something about the people and their civilizations who created these objects previously existed in that place. These artefacts can be found both on land and under the sea, and can range from spears made from mammoth bones to an entire city.
Archaeology exists because the wind and dust covers and exposes ancient relics by turns called erosion and stratification. Plants grow in the dust and fix these things more or less in the place that they were discarded. Sometimes, people simply destroy old buildings in order to build new things in the same place, and archaeological sites are routinely exposed in modern cities when new roads or drains are required.
Some of these 'city site' remains can be quite recent, whilst others date from the time when people first settled into agricultural routines and built the first towns and cities, which we think may have occurred about 50,000 years ago, when the remains of clothes, furniture fence-posts and fixed house foundations appear alongside earlier tools and weapons.
Dating archaeological 'finds'
We can discover when things got buried by a number of simple techniques: mainly by noticing the pattern of strata in the earth, and comparing that with growth-rings in trees that are buried nearby. As trees grow, they form rings, which are bigger in 'good' years and smaller in worse conditions. By comparing the size and nature of growth rings in trees of different ages we can build up a sort of 'historical calendar' of good and bad years.
Some other plants prosper in times that trees put down broad rings, others do better in the 'thin-ring' years. By comparing the seeds and plant debris in successive sedimentary layers, we can make an informed guess about when any particular layer was laid down, and thus the age of things buried within it. This science is called Dendrology (from Greek δένδρον, dendron, "tree"; and -λογία, -logia, to know).
Sometimes archaeologists are lucky, and find a scrap of pottery or art-work which will confirm or dispute their age assessment. This is often because similar pieces should appear in strata of similar ages.
More recently archaeology has advanced by the use of carbon dating. A naturally occurring radioisotope carbon-14 (14C) is formed in carbon-rich materials, and disintegrates slowly over time. By analyzing the rate of decay, it is possible to estimate the age of ash, plant and animal remains up to about 60,000 years old. By good luck, this seems to be about the time of the earliest truly human activity.
True or False?
However, archaeology is an art, as much as science! When sea-fossils were first found in mountains, they were thought to be 'figured stones' placed there by God for man's delight, rather than detritus from some ancient sea-bed, as now seems more probable. The truth is, we really do not know for sure. Scientists use the balance of probability that one conclusion is more likely to be right than several other, competing ideas.
That is why scientific researchers today always try to separate their observations from the methods and equipment they used to make measurements, and from their conclusions, so that later generations, with a better understanding, can review their evidence and improve our collective understanding of the past.
That is why, at school, in science, we are taught to use the five steps of scientific investigation. Let's use the Ma Wan Men as an example. First, we must observe the things around us - or the geographical environment, in this case. Ma Wan is a harbour, so people may fish there easily. Then we set a hypothesis, e.g. that a New Stone Age culture lived there. This is very probable as a neolithic culture had been found in nearby Sham Wan as well as in the Mainland.
Next, we must conduct an experiment to figure out whether our hypothesis is correct. However, we must, of course, find te artefacts before we can experiment! So the archaeologists used different tools to unearth tombs, pottery and other artefacts. They figure out that the finds may date back to 4000BC.* Then they think about the rock carvings that they found nearby. Perhaps people might go there for religious rituals, then go fishing! Then, if they go fishing, they might date back to at least the Middle Stone Age. Then they see traces of houses. Yes! It had got to be the old stone age. This process is called the 'recording' and 'analising' of data in science, and is a bit like the DBQs you face and fear in your history tests.
Finally, the archaeologists draw a conclusion that Ma Wan had been populated by an ancient people that was related to the Baiyue tribe (The one that Qin Shihuangdi conquered after conquering the states of Han, Zhao, Wei, Chu, Yan, and Qi. He built the Linqu for the soldiers so that they can fight, remember?)
Always remember! Science contains NO absolute truth NOR ANY incontrovertible wisdom. Rather it is a perpetual discussion and review between informed people with different experiences, from which balance of probability our collective human understanding will, we hope, improve!
*Though 4000BC is the time when the Metal Age started, remember that some places, such as Hong Kong, did not start their Metal Ages till 1500BC.