Structural Geology: Brunton: Declination

How to adjust the Brunton transit (compass) for magnetic declination.

This video covers online access to NOAA's magnetic declination calculator, how to use the calculator to determine magnetic declination for a field area, the seemingly backwards positions of "E" and "W" on the Brunton and the counterclockwise graduation of azimuth (0-360), as they relate to the adjustment for declination, a rationale for the declination adjustment, and how to make the adjustment.

Note that I misspoke at one point in the discussion of the magnetic declination calculator. Ater 1 year (January 4, 2022, not 2021), the magnetic declination on Signal Mountain, TN, would be 4° 53' W, considering that it's changing at a rate of 4' W per year. On January 4, 2021, when the video was made, the declination was 4° 49' W.

At the time that this video was posted, mid December 2024, NOAA's magnetic declination calculator was accessed at

https://www.ngdc.noaa.gov/geomag/calc...

This video was produced during the spring of 2021, at the heart of COVID, as part of my effort to teach a field methods class, partially online.

CHAPTERS (PARTS)
00:00 Intro
00:40 NOAA's mag. declination calculator
03:56 "E", "W", 0-360, backwards?
05:27 Rationale for declination adjustment
06:22 Making the adjustment