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In March, while visiting San Diego, I went to the San Diego Museum of Natural History in Balboa Park and toured the remarkable Cerutti Mastodon Site exhibit. This controversial exhibit of a mastodon site is notable for its claim that the mastodon’s bones were broken by humans 130,000 years ago, making it far older than any other such site in North America. The signs at the beginning of the exhibit read as follows; “The Cerutti Mastodon discovery. A San Diego find reveals the earliest evidence of of human life in North America. In 1992, paleontologists from the San Diego Natural History Museum were surveying a highway construction site to identify and salvage any fossils that might be unearthed. “Field paleontologist Richard Cerutti spotted some bones and tusks. Exploring further, the team discovered that these were bones of a mastodon-an extinct relative of elephants. “But Richard noticed something unusual. The bones were mysteriously broken and the pieces separated. “It took 22 years for scientists to solve the riddle. Once they did, they realized that this local site is evidence of human presence on this continent 130,000 years ago-much earlier than we thought possible. “In 2014, scientists made a new discovery about the age of the Cerutti Mastodon Site. How did this happen? Scientists figured out the age of the mastodon bones using radiometric dating. It’s a way of telling how old a rock or fossil is by measuring its radioactive isotopes. “A radioactive isotope transforms into an isotope of a different element over time. If you know the rate at which the “parent” isotope transforms into its “daughter” isotope, measuring the parent-daughter ratio tells you how old the material is. “Scientists used a method that measures the ratio of the radioactive isotope uranium-234 to its daughter isotope thorium-230. Dramatic improvements in this method have made it a highly accurate means of dating very old materials- up to 500,000 years. In 2014, scientists used this method to date bones at the Cerutti Mastodon Site. “The results were clear. The bones are approximately 130,000 years old.” More than two decades after the Cerutti mastodon’s discovery in southern California in 1993, USGS scientist Dr. James Paces was sent several bones of unknown age. The specimens were important because they came from a site with abundant evidence of processing by ancient humans. Advances in analytical capabilities and the understanding of processes that incorporate natural uranium and its decay products in fossil bone provided archaeologists with a radiometric dating tool that, at least in some cases, could confidently and accurately determine ages for these older materials. After analyzing nearly 100 subsamples from multiple specimens, Dr. Paces determined that the mastodon bones—which were still fresh when someone fractured them using hammerstones and rock anvils—were covered with sediments 131,000 years ago, give or take about 9,000 years. This result indicates that some form of archaic humans arrived in the Americas more than 100,000 years earlier than scientists had thought possible. Following the dating of the bones officials at the Natural History Museum began making plans for a permanent exhibit about the discovery. The exhibit opened in 2017. It is very thorough and includes bones, alleged hammerstones, and anvil rocks from the original mastodon site as well as numerous photos and interpretive panels. When J Harlen Bretz first announced in the 1920’s his theory that the scablands of eastern Washington State had been carved out by a cataclysmic flood he met stiff opposition. What he was proposing was so far out of the mainstream of geological thinking of the time that many scientists couldn’t accept it. Schooled in uniformitarianism they believed that earth’s landforms were all created by slow gradual processes operating over time and that an event of the magnitude Bretz was proposing just wasn’t possible. They tried to come up with alternative explanations for the facts Bretz presented that fit in with their current frame of reference. Yale University geologist Richard Foster Flint famously said of certain flood features in the scablands that they presented “a picture of leisurely streams with normal discharge.” The claim by San Diego’s Natural History Museum that the Cerutti site is 130,000 years old is likewise far outside what many scientists of our time are ready to accept. Other similar sites are much younger. For example Sequim’s famous mastodon site is only 13,800 years old. If the San Diego Natural History Museum is correct it totally rewrites the history books about humans in North America. It places humans in North America during a previous interglacial period. It would establish that humans had long since been in North America during the time of the comparatively recent ice-age floods. Critics of the Natural History Museum, and there are many, point to things like what they consider to be a lack of lithics from the site. Others speculate that the signs of bone breakage observed at the site may have been caused by some other creature besides humans or by modern day construction equipment. But the Natural History Museum counters that none of the critics have provided a satisfactory alternative explanation for the evidence that they’ve presented. Cerutti and his team of researchers and the San Diego Natural History Museum remain unequivocal in their conclusion: The Cerutti Mastodon Site is a 130,000 year old archaeological site. – by Mark Sundquist, Puget Lobe Chapter “Ideas without precedent are generally looked upon with disfavor and men are shocked if their conceptions of an orderly world are challenged.” J Harlen Bretz 1928 “Extraordinary claims require extraordinary evidence – each aspect requires the strongest scrutiny,” Chris Stringer