SCIENCE

A bolt from the blue has many powers. But until now, no one suspected that lightning can be a major sculptor of mountains. (National Geographic News)

Use our resources to better understand weathering, the process that shapes mountains through lightning and more familiar forces.

Discussion Ideas

• Read through the short Nat Geo News article. How did the scientists identify lightning-shaped areas in the Drakensberg range?
  • According to the article, “The tremendous amount of electricity in lightning leaves a magnetic signature so strong that the needle of a compass passed over a strike site often swings wildly. And compared with other rocks in the area, lightning-blasted fragments are harder, smoother, and more often free of lichens because they are freshly broken and sheared off in an instant.”

• What other forces are involved in weathering mountains and other features of a region’s landscape? Read our short encyclopedic entry on weathering for some clues.
  • Liquid water, ice, acids, wind, salt, plants, animals, and changes in temperature are all agents of weathering.
  • As noted in the Nat Geo News article, most mountains have been at least partially shaped by water.
    • glaciers carving through the landscape
    • erosion caused by the flow of rivers and streams
    • erosion caused by rain, snow, and other precipitation
    • “frost shattering,” described in the article as the process of frozen water expanding cracks in rocks that make up mountains

• Look at the topographic layer of our MapMaker Interactive. Using the zoom feature to navigate and identify landforms, choose a mountain range anywhere in the world—the Rockies, Andes, Alps, Urals, Himalaya, etc. What weathering forces do you think helped shape these mountains? Why? Do you think any ranges might be candidates for lightning-assisted weathering? Why?
  • The scientists in the Nat Geo News article suggest that mountain ranges in “warmer regions of Australia, Africa, and Asia” might be candidates for lightning-assisted weathering. These areas, they note, “were never heavily scoured by glaciers.”

Featured photograph by Andrew Taylor, National Geographic Your Shot http://ow.ly/siYRV