Saline Valley is located in the northwest corner of Death Valley National Park.
On a typical day military jets are conducting high altitude training--dogfights that can be heard but not be seen without the aid of high cloud cover. The jets also fly extremely low, often under 150-feet above the valley and the campgrounds at the Saline Valley Warm Springs.
From Wikipedia: Low-flying jet aircraft have long been common in the valley. The airspace over the valley is part of the US military's vast R-2508 Special Use Airspace complex. The Saline Military Operating Area (MOA) covers the entire valley south to Hunter Mountain from 200' AGL up to FL180 with an ATCAA located over the same area extending from FL180 up to FL600. The airspace is used by military aircraft primarily from Nellis AFB, Edwards AFB, NAWS China Lake, and NAS Lemoore for high and low altitude mission training.