The scientists used gravity and seismic measurements to figure out how thick the layers of soil and rock are in Yucca Valley. They found that the thickest layers are in a narrow trough in the eastern part of the valley. They also discovered a hidden ridge of rock that runs north from Mine Mountain to Quartzite Ridge. The rock is close to the surface, which could change how we think about water moving underground in the valley. By using seismic measurements, they were able to estimate the thickness of soil in some valleys. This information will help them choose where to drill for studying how water moves underground.