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Virginia Extensometers Depth Comparison

Detailed Description

How Deep Do We Drill?

USGS borehole extensometers extend from the land surface all the way down to the basement rock at the bottom of the aquifers they are monitoring. These boreholes can be hundreds to thousands of feet deep! This graphic shows how deep three of the extensometers on the Virginia Coastal Plain extend into the ground by comparing them to the heights of some of North America’s tallest buildings.

Extensometer Depths

  • Franklin Extensometer: 860 feet below land surface
  • Suffolk Extensometer: 1,620 feet below land surface
  • Nansemond Extensometer: 1,960 feet below land surface

Compare this to the heights of some of North America's tallest buildings

  • The Empire State Building: 1,454 feet
  • Central Park Tower: 1,550 feet
  • One World Trade Center: 1,792 feet
  • The CN Tower, Toronto: 1,815.4 feet

Extensometer sheds not to scale.


Public Domain.