SALT LAKE CITY (AP) — Rare salt formations have been documented for the first time on the shores of the Great Salt Lake, and they could yield insights about salt structures found on Mars before they disappear for good.

They're showing up now in part because water levels at the largest natural lake west of the Mississippi have been lowered by drought and water diversion, exposing more shoreline. It's a story that's playing out throughout the American West as a growing population puts more demand on scarce water resources.

Along the high-salinity waters Great Salt Lake, the expanded shoreline me...