Interestingly, it took quite some time for people to realize the significance of the pits. The earliest written record of the pits came in 1769 when a Franciscan friar wrote about them. The first published mention of ancient animals found at the pits came in 1875. Finally, the significance of the pits was fully recognized in 1905. Amateur and professional excavations took place in the coming years, the most of important of which occurred in 1913-1915 when the Natural History Museum of Los Angeles County (under its previous name) conducted thorough excavations that revealed 750,000 specimens. The most recent excavations came in 2006, which were collectively called Project 23. The nearly complete Columbian mammoth and numerous other specimens were discovered and are still being studied and processed.