Airborne geophysical survey: Baltimore 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.

本数据集包含沿飞行航线（flight lines）由机载仪器采集的航空磁测（aeromagnetic）与航空放射性测量（aeroradiometric）数据，此类仪器可同步记录磁场强度值、放射性参数及测点位置。其中，航空磁测数据集包含纬度、经度、海拔高度与磁场强度值，同时附带地质符号或编码，此类地质符号源自地表地质图（surficial geologic maps）。航空放射性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（以铋214为示踪）、钍（以铊208为示踪）、钾（钾40）、元素比值及辅助信息。