Dating Techniques
How do we know how old an artifact is? Before the advent of modern science, most dating was done via stratigraphy, based on the principle that the oldest remains are normally at the bottom of an excavation trench. Since the 1950s radiocarbon dating [also called C14 or 14C dating] has been a standard form of dating organic materials. All living organisms absorb two types of radiocarbon from the atmosphere. Once they die, no more radiocarbon is absorbed. Instead the radiocarbon begins to break down at a predictable rate. By measuring the amount of remaining radiocarbon, scientists can establish how long ago that organism died. Radiocarbon dating cannot be used to date non-organic matter such as stone.
A radiocarbon date is expressed in BP, which means “before present”. To complicate the issue, “present” is set at 1950, not the year we are currently. The radiocarbon date can then be converted to a calendar year. Every date has a statistical ] a certain number?uncertainty, which can vary. It is expressed as plus/minus [± 200 years means that the object could be 200?of years. For instance a date years older than the date given or 200 years younger. There are many other considerations with radiocarbon dates which you can explore by clicking on: http://archserve.id.ucsb.edu?Anth3/Courseware/Chronology/08_Radiocarbon_Dating.html
For a list of Canadian radiocarbon dates see Canadian Archaeological Radiocarbon Database (CARD).
Other means of dating are dendrochronology, and thermoluminesence. Iceland has yet another method, tephrochronology, dating by volcanic ash layers. Iceland has had a long series of volcanic eruptions, each of them depositing a layer of ash over a considerable area. The individual layers have been dated by organic objects trapped in them via the radiocarbon method. Because the ash of each eruption is distinct, these same layers can often be identified in other excavations where there is no organic material to date.
Dating an Object by its Looks
You can probably tell a 1980 Ford from a 2006 Mercedes. An archaeologist uses similar knowledge to establish when and where an artifact was made. Things like household utensils, weapons, tools, and ornaments change, however subtly, over time, making it possible to date an artifact by its mere appearance. We call this dating by typology. A time-honoured way to become familiar with such changes has been to visit and examine artifact collections in as many museums and other institutions as possible. Today, many of these artifact collections are posted on websites which can eliminate a lot of travel. Even so, being able and touch and handle the actual artifact remains the best way to learn.
Beyond their dates, artifacts provide many valuable clues to the past such as how they were made and where, made for, how they were used, and by what kind of person. Often only a fragment is needed to tell a much bigger story.
Below you will be introduced to a single category of artifacts: axeheads from different places and different time periods. You may wish to refer back to them when looking for clues to Vinland.
