Airborne geophysical survey: Hardin 1° x 2° Quadrangle

Aeromagnetic and aeroradiometric data were collected along flight lines by
instruments in an aircraft that recorded magnetic-field and radiometric
values and locations. The magnetic data set presents latitude, longitude,
altitude, and magnetic-field values. Geologic symbols or codes are also
included. The geologic symbols were picked from surficial geologic maps.
The radiometric data set presents latitude, longitude, altitude, geologic
symbols or codes, apparent Uranium (Bismuth 214), Thorium (Thallium 208),
and Potassium (K 40), the element ratios, and ancillary information.

航空磁测数据（aeromagnetic data）与航空放射测量数据（aeroradiometric data）由机载测量仪器沿飞行航线采集，同步记录磁场数值、放射测量数值与位置信息。
该磁测数据集涵盖纬度、经度、海拔高度与磁场强度数值，同时附带地质符号或编码，此类地质符号均取自地表地质图。
航空放射测量数据集则包含纬度、经度、海拔高度、地质符号或编码、表观铀（铋214）、钍（铊208）、钾（钾40）的元素含量及其比值，以及辅助信息。