ANTH 024 1st Edition Lecture 5Outline of Last Lecture I. Site Formation, Preservation, and Excavation Outline of Current Lecture II. Archeological Dating A. Absolute Dating vs. Relative Dating Current LectureI. Archeological Datinga. Absolute (Chronometric) Dating i. Lets you know exactly how old something is (with an error range) ii. Examples: radiocarbon dating, potassium-argon, thermoluminescence, dendochronology) b. Relative Dating i. Puts things in order from oldest to youngestii. No calendar dates iii. Examples: stratigraphy, seriation/stylistic sequences iv. Law of Superposition can be used v. Stylistic Change1. Why are there stylistic changes?a. Technology changesb. People’s sense of style changes2. Christian Thomsen’s Three Age System was created after he noticed stylistic differences in the artifacts at the museum he worked at vi. Seriation1. Process of building a history of artifacts from the oldest to the youngest 2. When a style changes, the old styles don’t disappear right awaya. It takes a while for older styles to disappear, so there is a time when the two exist at the same time3. The curves that represent change in style over time are called battleship curves (named by Deetz)4. Deetz studied New England gravestones and their stylistic changes, and how they varied across New Englandc. Absolute DatingThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Historical References1. Some sites have specific calendar dates on them2. Others have the names of a ruler ii. Dendochronology1. Certain trees (sensitive species) add a ring ever year a. The appearance of the ring differs according to changes in climate, like droughts or firesb. Can find the year of a documented drought/fire/climactic event by examining pieces of wood at sites iii. Radiometric (Radiocarbon) Dating 1. There was a constant proportion of Carbon-12 to Carbon-14 in theatmosphere for most of history (or was there? See calibration bullet)2. Carbon-14 is an unstable isotope that loses neutrons over timea. It has a constant rate of decay (half life)3. You can measure the rate of decay and date the samplea. Need a large piece of charcoal to use as a sampleiv. Accelerator Mass Spectrometry (AMS)1. Radiometric dating methods, but with better technology2. No longer need to use a big piece of charcoala. Can use a small piece of a textile, papyrus, etcv. Calibration 1. Found that the ratio of C-12 to C-14 has actually changed over time because of variations in solar radiation a. Can compare radiocarbon dates to the curve of the changing ratio and find the real date vi. Carbon-14 Dating, some broad points: 1. It can date any kind of organic material 2. Dating works back to about 50,000 years ago a. We don’t have tools refined enough to detect traces beyond this3. Dates should be given in years BP (Before Present)a. The present is 1950 i. Nothing after 1950 can be carbon dated because atomic weapons testing and use changed the amount of radiation in the atmosphere, and thus the proportion of C-12 to C-144. All radiocarbon dates have error