January 4, 2019
The mechanics of how the sounds were generated was unclear, their sensors picked up and measured the strength of the vibrations around them. Filtered through their helmets what they heard was muted but they could isolate repetitions of some tones and phrases. Some sounds had started and seemed to cascade and resonate only when they entered the valley. Standing, each facing a different direction, they listened tried to triangulate the source, eliminate echoes. There might be multiple sources and layering recalled patterns of the call and response of birds, but they hadnít enough information to even rule out geological origins.