How was the Ohalo Camp preserved as noted in the nonfiction book, Unstoppable Us?

As noted in the book, the Ohalo Camp was preserved by mud. Discovered on the shores of the Sea of Galilee, the author notes that people lived in that camp 23,000 years ago. The remains of the camp’s garbage dump taught the archaeologists what the people who lived there ate, and the huts in which the people lived, which were also preserved, taught archaeologists about the people's daily lives.