The USGS collected data from 811 gravity stations on the Lake Mead 30 by 60 quadrangle.Density and magnetic susceptibility measurements were also performed on more than 250 rock samples.

• 美国地质勘探局利用30*60的网格阵采集了811个重力点的数据，并且收集了250多个岩石样本的密度和磁化率数据。