This is a community of those using "Building Foundations of Scientific Understanding"

Elementary Science Education

How are fossils dated?

Viewing 0 reply threads
  • Author
    • #4609

      Bernard Nebel

      The ages of fossils are commonly given (300, 200, 100 million of years ago). Students should ask: How are such ages determined? There are several methods briefly described at:

      Radiometric dating is described in following video

      Geological features known as synclines and anticlines (Type into your browser: synclines anticlines images) provide evidence for how the Earth’s surface has been folded and contorted over the ages. Such folds enable the estimate for the height of ancient mountains now eroded away. Knowing average rates of erosion provide additional estimates for age.

      Likewise geological features of southwest united states are indicative of high plateaus now eroded away. (Type into your browser: geological features of southwest images). Again, rates of erosion provide an indication of age.

      Matching estimates of age obtained from different methods gives further evidence for their reality.

      Another age indicator: Coral reefs and limestone

      When we examine the corals of living coral reefs, we find that they are really “homes” of millions of tiny animals as seen in the following video,

      As shown in the video, the animals secrete a bone-like material around themselves, This is the coral (calcium carbonate or limestone).  At many locations on land, we find vast beds of limestone rich in fossils of the types of animals common to corral reefs. These beds of limestone can only have been formed by corals and associated organisms living in shallow ocean waters over millions of years. By later earth processes some these beds of limestone rich in fossils were uplifted so that now they are well above sea level. The following video gives one example

Viewing 0 reply threads
  • You must be logged in to reply to this topic.