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Archeology for Interpreters > 5. How Do Archeologists Figure Out How Old Things Are?

Artifacts as time markers

Glass bottles

(photo) Clear, green blue white and brown bottles recovered from the Pantheon Saloon.

Bottles recovered from the Pantheon Saloon Complex, Klondike Gold Rush National Historical Park. (NPS)

Glass bottles clearly demonstrate technological change through time. Archeologists can date sites by identifying characteristics of glass bottles they recover.

The majority of glass bottles found on colonial American historical sites were hand blown in England or France (NoŽl Hume 1970: 60). Between 1650 and about 1814, hand-blown bottle shapes evolved to the point that archeologists can tell the differences between them with little trouble. Some of these early bottles bear the seals of their original owners, making identification possible.

Glass manufacturers began making bottles in molds in the early nineteenth century. Molded bottles were produced quickly in standardized sizes and shapes. Early in the century lips were applied by hand but this process was mechanized by 1903. Many nineteenth- and twentieth-century bottles are embossed with information about the manufacturer. These maker's marks allow archeologists to date bottles and often reveal information about their original contents.

Try it yourself

Bottle Analysis
In Activity 1 at this web site, you can answer questions to compare three bottles from different time periods.

Use What You Know: Assess Your Knowledge (#5 of 9)

What methods do archeologists use to date archeological contexts? What kinds of materials are useful to archeologists for dating contexts or sites?

How might you illustrate the principals of seriation, stratigraphy, or other methods for visitors to your park?