Final answer:
The Great Salt Lake Desert and the Great Basin Desert are the two deserts located where the prehistoric Lake Bonneville used to be.
Step-by-step explanation:
The two deserts that are located where Lake Bonneville once was are the Great Salt Lake Desert and the smaller but nearby Great Basin Desert. The Great Salt Lake Desert is mainly known for its vast salt flats, a remnant of the large prehistoric Lake Bonneville's dried-up saline waters.
The Great Basin Desert, on the other hand, is part of the larger Great Basin which extends across Nevada, Utah, and portions of other surrounding states. This desert is characterized by its sagebrush and sparsely vegetated expanses. Both deserts present harsh, arid conditions that contrast starkly with the ancient lake's once-abundant aquatic environment.