Explanation
In a typical river delta, the narrow end of the delta is located at the point where a river enters a delta, with a wide fan-shaped sedimentation region extending outward into the body of water into which the river empties. In some rare cases, the delta is located at the waterway's exit from a large, flat valley, yet still inside the valley. The sediment is dropped within the valley and the clear water then exits into a bay or the ocean, so the apex of the delta is at this exit, a configuration said to be inverted from that usually seen. Inverted deltas typically do not last long in geological terms, since they tend to fill up with sediments rather quickly and eventually become normal deltas.
Read more about this topic: Inverted River Delta
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