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How did Lake Chad change during the late Pleistocene and early Holocene?

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A detailed geologic time scale chart displaying Earth's history from the Hadean Eon over 4.5 billion years ago to the present, organized by eons, eras, periods, epochs, and ages with color-coded columns and corresponding dates in millions of years. — Holocene Epoch The stratigraphic chart of geologic time.

During the late Pleistocene and early Holocene, Lake Chad underwent a dramatic transformation, expanding into a massive inland sea known as Mega-Chad. Driven by a significant increase in rainfall and monsoonal activity across tropical latitudes, this ancient lake covered an area of approximately 130,000 square miles (336,700 square km).12

At its peak in the early Holocene Epoch—potentially persisting until about 7,000 years ago—the lake reached an elevation of roughly 1,100 feet (335 meters) above sea level, making it about 180 feet (55 meters) higher and up to 550 feet (170 meters) deeper than it is today. During this period, the lake was so expansive that it overflowed southward, eventually draining westward into the Benue River and toward the Atlantic Ocean.1

This vast water body persisted in the region through the very late Pleistocene and up until approximately 5,000 years ago. Today, the remnants of this period are visible in the form of older dune systems that were once flooded by the lake, which now appear as linear islands or are found within interdunal hollows filled with lake sediments.21