Airborne geophysical survey: Spotsylvania '60 and '64, Virginia

Aeromagnetic data were collected along flight lines by instruments in an
aircraft that recorded magnetic-field values and locations. In the earlier
days of surveying, the only way to represent this data was to generate an
analog map with contour lines. This dataset is a representation of the
digitized contour lines either by following the lines or by choosing the
intersection of the contour and flight-line to create a value of the magnetic
field. The values presented are latitude, longitude, and map magnetic-field
values.

航空磁力数据（aeromagnetic data）由搭载于飞行器的探测仪器沿飞行航线采集，同步记录磁场强度值与位置信息。在航空磁测的早期阶段，此类数据唯一的可视化表达方式为绘制带有等值线的模拟地图。本数据集为数字化等值线的成果表达，可通过沿等值线追踪，或选取等值线与飞行航线的交点来获取对应的磁场数值。本次发布的数据包含纬度、经度与航磁图磁场强度值。