The bones of a juvenile Ice Age Columbian mammoth have been found in a field near Castroville, the first discovery of its kind in Monterey County.

The remains were uncovered by earthmoving equipment in December, said Mark Hylkema, Santa Cruz District archaeologist for the state Department of Parks.

The precise location of the find is being kept under wraps to discourage souvenir hunters from damaging, looting or contaminating the site.

Hylkema has specialized in the study of Native American culture on the Central Coast.

He is recommending that a controlled excavation of the site be done “with a particular goal of looking for evidence of archaic Native American butchering or burning” in the event that the elephant-like creature was brought down by Ice Age hunters.

The equipment operator, Martin Jefferson, was clearing land to expand a field for agricultural tillage when his tractor blade scraped against what appeared to be a large tusk, Hylkema said, and recognized the bones as similar to that of a mammoth.

Other bone and ivory fragments included a large molar-like tooth which Jefferson removed from the clay, Hylkema said, and he then notified the property owners who called state parks Ranger Nel Lyons, who in turn reported the find to Hylkema.

Hylkema, along with field assistants Dawn Johnson and Jorge Aguilar, visited the site Dec. 14 and found more remains. Hylkema described teeth, tusks and bones as still porous and in good condition.

“There were three types of bone conditions noted,” Hylkema reported. “Fragments of ivory tusk, regular looking bone fragments and some that were discolored as though charred or lithified.”

If the bones are charred, he said, it could indicate human association with the remains. Some bone fragments were taken for radiometric tests to determine how old they are.

Ancient Native Americans had specialized tools — heavy spears tipped with points designed to penetrate and bleed out large mammals — and finding such an artifact would indicate the Castroville mammoth was hunted and killed for food. So far, he said, no human artifacts have been found at the site.

The soil level and composition in which they were found indicates that the mammoth died 10,000 to 25,000 years ago, Hylkema said.

Many such finds are discovered on privately owned farmland when soil is worked, he said, and archaeologists depend on the generosity and hospitality of farmers for access to the sites.

Mammoths roamed North America for more than 1 million years and died out about 10,000 years ago, Hylkema said, about the time the first humans began populating the continent.

Meanwhile, he said, “the mystery is bigger than the reality” at the site. There is no complete skeleton to see, just scattered pieces of bone, tooth and tusk. The dig is an unfunded, volunteer effort in “one of the most challenging expeditions I’ve ever done,” because of the logistics and the “absolutely awful” weather.

The property owners want to do spring planting and he and his team, Hylkema said, are racing to finish by next month.

The Pacific Grove Museum of Natural History has mammoth teeth and tusks among its exhibits, said museum executive director Lori Mannell.

The Castroville discovery “is very exciting,” she said. “There is potential there for a nice regional find. Where you find one fossil, you can find more.”

She and Hylkema said the museum has not participated in the discovery, but, Mannell said, “we would love to get involved.”

Kevin Howe can be reached at 646-4416 or khowe@montereyherald.com.