What was SV area like 10,000 years ago?
By Lisa Levinson
Scotts Valley Banner
August 15, 1990

Picture the scene: heavily forested mountains dipping down into marshy valleys spotted with lakes and gushing artesian springs. Indians live in villages around the largest lake hunting deer, elk, geese, and other wildlife. Occasionally, they trek to the distant ocean and collect shells and special rocks to make stone tools.

This is what life was like in Scotts Valley 10,000 years ago, according to archaeologist Dr. Robert Cartier who excavated the prehistoric indian village site beneath the city hall from 1982 through 1987.

"There are only 50 to 100 sites this old in the United States," said Cartier. "But this is probably the only one where people lived in one spot for over 10,000 years."

Since then, smaller sites have been found surrounding the ancient lakebed. "There are at least a dozen sites in Scotts Valley proper and the Mount Hermon area. We probably haven't found two dozen of them yet. Twice as many we won't ever find," Cartier said.

Archaeology and construction go hand in hand in Scotts Valley. "Construction is the catalyst that opens the book so we can read the past, " said Cartier.

But Cartier said he has mixed emotions about building, which both destroys and reveals archaeological sites. "Ironically, our society sets aside founding to understand what's lost during construction, allowing us to make incredible scientific discoveries."

Traces of prehistoric activity were found beneath Seagate Technology during its construction. Recently, archaeologists surveyed Glenwood Estates for artifacts. Although archaeologist Matthew Clark who conducted the survey said he didn't find clear evidence of occupation, he recommended that an archaeologist be present during construction on the property.

"It looks like there ought to be more artifacts than we found, so someone should watch just in case more are discovered," Clark said.

Scotts Valley has many archaeology sites because it was once on the shore of an ancient lake.

The lake's edge was where the water district office now stands. Cartier estimates between 5,000 and 15,000 years ago geologic activity caused landslides that plugged up Carbonero Creek with debris, creating a natural dam.

But the lake started to dry up when the latest ice age ended. As the lake receded, indian villages moved from the city hall site toward Carbonero Creek.

"It is a cyclical lake," Cartier explained. "It dried out and will fill up again, but not in our lifetime. We are now in the driest time of the ice ages."

Who lived around the lake before it dried out? Archaeologists suspect that many different indian peoples inhabited the Scotts Valley region on and off until the Ohlone settled the Santa Cruz region around 2,000 years ago.

"They didn't leave us their names," chuckled Cartier as he explained how archaeologists distinguish one ancient indian group from another, addressing each with a hypothetical name.

The first known people to inhabit the area around 13,000 years ago were the so-called Aruama Indians. Based on artifact similarities, Cartier says these people probably came from Asia.

The San Lorenzo Indians were the next group to arrive around 11,000 years ago. Then came the Umunhum Indians 8,000 years ago and the Scotts Valley Indians 6,000 years ago.

Artifacts, like stone tools or cooking instruments, tell the archaeologist how old a site is and differences between the way they were made tell whom lived in it, said Cartier.

While excavating the city hall site, local college students and other volunteers unearthed approximately 10,000 artifacts, like spear points, food processing tools, and charcoal samples from campfires. A sandstone metate, for grinding nuts, was so old it crumbled to dirt.

Due to the acidity of the soils in Scotts Valley, no bones, shells or wood was recovered.

Cartier and his team used three techniques to date the artifacts: radiocarbon testing, obsidian hydration, and artifact typing.

Radiocarbon testing works because organic material loses electrons over time, Cartier said. All living things take in proportionate amounts of radioactive and ordinary carbon dioxide from the atmosphere or from eating plants, but after death the radioactive carbon decays.

Knowing the average rate of this decay, called the half-life, and measuring the amount of radioactive carbon left can tell archaeologists how much time has passed since death, providing them with an absolute date.

"The laboratory results from the charcoal samples were really a surprise to us," Cartier said. "We didn't expect anything over 4,000 years old, but the results showed at least 9,000 years old." Initially written off as a laboratory error, repeated tests showed these results were correct, making national news.

Obsidian hydration was used to determine when tools were made. Obsidian is a type of rock that absorbs water at a constant rate along exposed edges. The amount of water, seen as a darkened band across the rock's edge under a microscope, is proportional to the age of the cut.

"It looks like a cross section of an orange," said Cartier. The larger the darkened band, analogous to the orange peel, the older the tool.

By comparing artifacts with others of known ages from Northern American sites, Cartier could date them. "Some artifacts were so similar they looked like they were from the same mold," he said.

Artifact typing of stone tools indicates local indian groups gathered stone from Ano Nuevo State Beach and traded with Sierra Mountain Indians.

Using these techniques, Cartier and his team recorded the coming and going of various indian groups. Their results will also help other archaeologists.

"This is the oldest site from Santa Barbara to Oregon, so archaeologists can date the whole central coast from Scotts Valley," he said calling City Hall the vantage point for linking the present to the past.

Here, gophers dig up ancient indian tools beside the original Scott House, built by Hiram Scott in 1853, while city officials take care of local business in the building next door.

Visitors can see some of the artifacts and pictures explaining the excavation process on display at the Scotts Valley City Hall.