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The first statewide geologic map of Georgia was published in 1825. It was a 1:1,000,000 scale map of Georgia and Alabama published by Henry Schenck Tanner. [3] In 1849 W.T. Williams published the geological features for the state on a 1:120,000 scale map within George White's (1849) Statistics of the State of Georgia report. [4]
A magnetic field is a vector field, but if it is expressed in Cartesian components X, Y, Z, each component is the derivative of the same scalar function called the magnetic potential. Analyses of the Earth's magnetic field use a modified version of the usual spherical harmonics that differ by a multiplicative factor.
This is a specific example of a general rule that magnets are attracted (or repulsed depending on the orientation of the magnet) into regions of higher magnetic field. Any non-uniform magnetic field, whether caused by permanent magnets or electric currents, exerts a force on a small magnet in this way.
The Earth's magnetic field protects the Earth from the deadly solar wind and has long been used for navigation. It originates in the fluid motions of the outer core. [24] The magnetic field in the upper atmosphere gives rise to the auroras. [26] Earth's dipole axis (pink line) is tilted away from the rotational axis (blue line).
When non-migratory big brown bats (Eptesicus fuscus) are taken from their home roosts and exposed to magnetic fields rotated 90 degrees from magnetic north, they become disoriented; it is unclear whether they use the magnetic sense as a map, a compass, or a compass calibrator. [69]
The World Digital Magnetic Anomaly Map (WDMAM) was first made available by the Commission for the Geological Map of the World in 2007. Compiled with data from governments and institutes, [1] the project was coordinated by the International Association of Geomagnetism and Aeronomy, and was presented by Mike Purucker of NASA and Colin Reeves of the Netherlands. [2]
With a local declination of 14°E, a true bearing (i.e. obtained from a map) of 54° is converted to a magnetic bearing (for use in the field) by subtracting declination: 54° – 14° = 40°. If the local declination was 14°W (−14°), it is again subtracted from the true bearing to obtain a magnetic bearing: 54°- (−14°) = 68°.
name = Georgia Name used in the default map caption; image = USA Georgia location map.svg The default map image, without "Image:" or "File:" image1 = USA Georgia relief location map.svg An alternative map image, usually a relief map, which can be displayed via the relief or AlternativeMap parameters; top = 35.2 Latitude at top edge of map, in ...