Leaf Fossil in Cement
March 10, 2011
Photographer: Mario Freitas
Summary Author: Mario Freitas
In scientific education, analogies play a decisive role. A quite simple observation may allow students to learn about natural processes in a more straightforward way if the understanding of such processes involves much shorter timescales. Normally, remaining traces of parts of a living being are categorized as fossils only if they date from a remote time, such as 10,000 years ago or longer. The printed leaf depicted above, however, was made only a few years or decades ago. In this case, what we would call the fossil record, instead of naturally precipitated sediments, was a man-made layer of Portland cement on a sidewalk. A small branch with two leaves likely fell from its parent tree and was brought here by the wind while the cement layer was still fresh. Afterwards, the leaf vegetal tissues vanished due to exposure and weather conditions. Note, the vein pattern suggests that the leaves belong to a guava tree found in the neighborhood. The study of fossils by paleontologists is a major contributor to the knowledge of prehistoric life on Earth. But beware of fake fossils and purveyors peddling fossil frauds. Photo taken in Brasilia, Brazil, on January 18, 2010.
Photo details: Camera Maker: Canon; Camera Model: Canon PowerShot A710 IS; Focal Length: 5.8mm; Aperture: f/4.0; Exposure Time: 0.0008 s (1/1250); Exposure Bias: none; Metering Mode: Matrix; White Balance: Auto; Flash Fired: No (enforced); Orientation: Rotate 270; Color Space: sRGB.