Tree Ring Dating Simulation - Student Activity Kit
Modified with permission from Global Change: Time and CyclesDepartment of the Interior, U. Geological Survey, Reston, VA, USA. In this activity, students will use pre-marked paper strips to simulate tree-ring core samples to help them understand that data for past climate changes can be gathered from sources beyond long-term weather observations. Students will be able to recognize the direct impact of climate on annual tree growth patterns.
Trees contain some of nature's most accurate evidence of the past. Their growth layers, appearing as rings in the cross section of the tree trunk, record evidence of floods, droughts, insect attacks, lightning strikes, and even earthquakes. Each year, a tree adds to its girth, the new growth being called a tree ring. Tree growth depends upon local conditions such as water availability. Because the amount of water available to the tree varies from year to year, scientists can use tree-ring patterns to reconstruct regional patterns of drought and climatic change.
This field of study, known as dendrochronologywas begun in the early s by an American astronomer named Andrew Ellicott Douglass. During wet, cool years, most trees grow more than during hot, dry tree ring dating simulation worksheet and the rings are wider. Drought or a severe winter can cause narrower rings. If the rings are a consistent width throughout the tree, the climate was the same year after year. By counting the rings of a tree, we can pretty accurately determine the age and health of the tree and the growing season of each year.
Modern dendrochronologists seldom cut down a tree to analyze its rings. Instead, tree ring dating simulation worksheet samples are extracted using a borer that's screwed into the tree and pulled out, bringing with it a straw-size sample of wood about 4 millimeters in diameter. The hole in the tree is then sealed to prevent disease. Computer analysis tree ring dating simulation worksheet other methods have allowed scientists to better understand certain large-scale climatic changes that have occurred in past centuries.
These methods also make highly localized analyses possible. For example, archaeologists use tree tree ring dating simulation worksheet to date timber from log cabins and Native American pueblos by matching the rings from the cut timbers of homes to rings in very old trees nearby. Matching these patterns can show the year a tree was cut, thus revealing the age of a dwelling. To investigate the extent, speed, and effects of historical climate changes locally and globally, scientists rely on data collected from tree rings, ice cores, pollen samples, and the fossil record.
Computers are used to detect possible patterns and cycles from these sources. In dendrochronology, large databases allow scientists to compare the ring records of many trees, construct maps of former regional climates, and reveal when, where, and how quickly the climates changed. These historical records are extremely valuable as we struggle to understand the extent and nature of any possible future climate change. In this activity, students will use pre-marked paper strips to simulate tree-ring core samples.
They'll work in groups to reconstruct a year climatic history. The students will align all four samples so tree ring dating simulation worksheet the patterns match. Then they'll determine the year when each tree was cut and when it began to grow. They'll count all of the rings from the oldest samples as they are aligned with the younger samples to determine the total amount of time represented by the rings.
They should count aligned rings that appear on several samples only once. You many want to tell the students that the pith central layer and bark are not counted in determining the age of a sample. The youngest ring is closest to the bark and the oldest ring is closest to the pith. The answers to some of the questions will tree ring dating simulation worksheet upon the class, for example, when the students were born.
In looking at the climate record as revealed in the tree rings, notice that there is a significant period of poor growing conditions in each of the four decades covered by the tree samples. This pattern, which can be graphed, is the type of pattern scientists might look for when studying climate change. When you're finished with the activity, click on To Student Guide or Back to Activities List at the top of the page.
A set of paper strips pre-marked with ring patterns. Use the graphic below, either printing it out from this page or linking to another page where the graphic is larger and by itself. Make a copy for each online dating truro ns. Then cut the paper strips apart and if you want to make them sturdier glue them onto light cardboard or sturdy paper file folders would work well too. For a more realistic sample 'core' you may want to consider using straws or wood dowels.
Be aware that the preparation time will be much longer and more tedious.