In the course of the survey the group located a number of promising sites. One, in the form of a roughly circular mound a foot high and 100 feet in diameter located 10 miles northwest of the town of Novato, was designated Marin-374. Two test excavations were promptly made: a circular pit approximately 20 feet in diameter, where a shelter had once stood, and a rectangular pit three feet wide and six feet long just south of the circular pit. A student, Peter Moore, was made responsible for digging the rectangular pit. Although these pits produced a number of artifacts, the archaeologists decided to move on to more productive sites. By this time, however, Moore had become deeply engrossed in the work; he sought and obtained the permission of the archaeologists and the owners of the land to continue the dig. With the help of John MacBeath, a social studies teacher at the Novato Senior High School, he recruited several small teams to assist in the work and eventually helped to organize the Novato Senior High School Archaeology Club. The club, with Moore as president and in close cooperation with the archaeologists, completed a detailed analysis of Marin-374 early this year. The results of the project are reported by Terrence Jay O'Neil, who joined the club in 1966.

"I was not allowed to do any digging at Marin-374 until I had been exposed to a series of informal lectures on technical procedures," he writes. "In time I became responsible for mapping the site, preparing drawings of artifacts, analyzing materials and editing the final report. Approximately 40 club members had participated in the excavation by the time the work was finished.

"Marin-374 is a so-called single-component site: a deposit made by people who set up a complex of dwellings, remained for a time and then disappeared. Our findings indicate that Marin-374 became a dwelling place between 2,000 and 3,000 years ago. The Indians who made and used the objects were the coastal Miwoks, who spoke the language of the Hokan group of California Indians and were descended from early settlers who established small camps in the San Francisco Bay area at least 5,000 years ago. The relative richness of the area encouraged loose tribal organization. Groups of one or two families could maintain themselves on small sites, and f larin-374 marks a site of this kind.

"The soil of the site is fine-grained, with a large amount of black organic material that contrasts with the light-colored soil nearby. In dry weather this 'midden,' when disturbed, turns into a powdery gray dust that makes excavation unpleasant in summer. The area supports foot-high field grasses, including Russian thistle, and about 25 buckeye trees, two of which stand within the boundary of the site. These trees are very old; their immediate ancestors doubtless predated historic times. San Antonio Creek, which forms the northern and western limits of Marin-374, tends to reach flood stage in early spring, but it seems not to have eroded the midden. Examination of sediments in the first four inches of the site material indicated that the topmost layer of soil had probably never been disturbed. Leaching by rain had not significantly altered the location of artifacts, as far as we could tell, nor did we find large numbers of rodent burrows-all of which led us to believe Marin-374 was an undisturbed site.

"Archaeologists have developed two approaches to excavation. In either case one begins by driving a stake that serves as a reference mark from which measurements are made, and outlining rectangular areas, usually in the pattern of a numbered grid. In the case of 'micromethodology,' the rectangular areas are then excavated one layer (about four inches thick) at a time, and the location of each artifact is recorded by exact measurements on a three-dimensional grid. In the case of 'macromethodology,' pits that measure 10 feet square are dug out in foot-thick layers and artifacts are located and recorded only by pit and layer. Scrupulous controls are maintained in all phases of excavation and record-keeping. Undisturbed soil is closely examined for any texture and discoloration that might suggest a disintegrated artifact. All soil is screened and from the screenings materials are sorted according to type (shell, bone and so on). Artifacts are inspected, described, logged and labeled for storage. In micromethodology the ratio of area processed to man-hours is low; macromethodology stresses examination of the largest possible amount of material per man-hour.

"We learned that the area of the site was scheduled to become a trailer park but that the bulldozers would not move in for some months. At the suggestion of the supervising archaeologists we laid out a grid of intermediate size that could be worked within the scheduled time. After the boundary of the site had been determined through an examination of the soil, trench lines were laid out with broad undisturbed strips between them 'so that representative samples of the entire site would be dug for study. In general the pits were six feet square. In one case they were arranged in the form of an L [see illustration right]. The soil was removed, in 10-inch horizontal layers, with trowels and shovels. All measurements were made in metric units to within a tolerance of 10 centimeters. Two people were assigned to each pit, one digging a shovelful at a time while the other screened and examined the material. (There are advantages to washing the soil through the screen with water, but San Antonio Creek was almost dry, and so our materials were sifted dry.) Bits of bone and other animal remains, together with fragments of rock, were collected in bags labeled according to level. Each artifact of value was labeled and listed: its pit and level number, its location and its description. Club members had been trained to recognize projectile points, scrapers, pottery and modified stone.

"Hundreds of objects were uncovered.

As we subsequently learned, the collection includes most of the types of implements that were used by the coastal Miwoks during the final stage of their cultural development. Represented in it, by class, are hunting implements, tools for preparing food and making clothes, adornments, trading goods, ceremonial items and at least one house floor.

"Blades of chipped stone that were used for scraping constitute the largest single group of artifacts. A very few display remarkable craftsmanship but most are nonsymmetrical and otherwise carelessly made-generally by chipping one or more fragments from the edge of a natural fracture in obsidian, chert or other local rock. Others were improvised from broken projectile points, and one blade was made from a fragment of pottery.

"Projectile points make up the second most numerous type of artifact, and their workmanship is somewhat better than that of similar points found in other Marin County sites. Some, which appear to be unique to this site, have sawtooth edges, a notch at one corner and a concavity in the base. The points range from about two inches in length down to less than an inch. Many spearpoints were recovered, of which a few representative types are depicted in the accompanying drawing [see Figure 4].

"The collection includes 16 mortars and fragments of mortars, the largest of which is 32 inches in diameter. They were excavated at an average depth of about 18 inches. Two have round bottoms and round rims. Three have flat bottoms and flat rims and range in weight from 2 1/2 to 45 pounds. Nineteen pestles were recovered, 13 of which were conical in form, five cylindrical and one globular. They were made of various native rocks, including basalt, sandstone, diorite and andesite. One bore asphaltum stains.

"A total of nine charmstones were excavated at an average depth of about 15 inches. Most were phallic types, and several had partial coatings of asphaltum. Ornamental artifacts included pennants made of shell and an earplug of steatite. Fragments of nine pipes were also found. One, of white serpentine, is excellently made and bears attractive ornamentation.

"Beads of various kinds and sizes were common. Some were made from the bones of birds; the largest was 1.5 inch in length and .4 inch in diameter. (The smallest complete bead measures a mere .06 inch in diameter-indicating the care with which the soil must be screened to ensure the recovery of interesting materials.) The collection includes various beads made from the shells of marine animals, particularly clams and olivellas; perforated disks of clamshell make up the majority. Eight stone beads made of black steatite, marl limestone and slate were found. The largest, of carved steatite, was found at a depth of 20 inches. Three beads turned up that could not have been manufactured by the limited technology of the Miwok culture. One is made of a translucent, iridescent blue glass and is oblong in shape. Another, of the same general shape but more crudely formed, is of a red glassy material that has been glazed. Both of these beads were found at a depth of eight inches. The third is of a porous, translucent yellow glass and is almost perfectly spherical; it was found at a depth of 28 inches. Obviously these beads are trade items from Spaniards or other white pioneers. Other 'foreign' objects, found near the surface, were a piece of iron in the form of a slender U, thickened in the curve portion, and two forged nails of the type commonly used during the first half of the 19th century.

"Contact between the Miwoks and the white pioneers is also indicated by a profusion of porcelain fragments in light blue, dark blue, yellow and white. Some fragments are well glazed and carry designs of thin lines in dark blue. They were found mostly on the surface and to a depth of a few inches. They have been tentatively identified as parts of l9th-century Spanish cups, bowls and plates. One white fragment had been modified by secondary chipping to serve as a scraper.

"Perhaps the most interesting evidence of foreign technology was a Minie ball found at a depth of 10 inches in pit 3-C. The somewhat dented end and the rifling marks indicate that the bullet was fired from a gun and either hit a soft, resilient surface or fell at low velocity at the end of a long flight [see drawing at bottom right in Figure 4]. We were tempted to use this artifact as a method of dating material at the 10-inch level. The Minie ball was developed by Captain Claude Etienne Minie of the French army in 1849 and quickly circled the globe. It marked a distinct advance in arms technology, since the force of the exploding charge expanded the bullet to form a gastight seal against the bore of the gun, conserving the compressed gases and increasing the bullet's muzzle velocity and killing power. Bullets of this type were in wide use in the U.S. from about 1860 to 1880. Other evidence, however, suggested a much older date for the layer in which the Minie ball was found, and it may have buried itself to this depth on impact.

"One of the most interesting artifacts turned out to be a small slab of clay that bore the impression of a woven basket. This fragment was examined by Lawrence E. Dawson at the Robert H. Lowie Museum of Anthropology of the University of California at Berkeley, who made a positive reproduction of the depressions by pressing potter's clay against the slab. The weave is much finer than the weave in similar baskets found elsewhere in California: 10 weft courses per inch and 7.6 warps per inch. In Dawson's opinion the basket was made of the split roots of a local grassy plant that resembles sedge and was so tightly woven that it must have been watertight.

"No human burials had been made at Marin-374, although one group of bones was found that appear to be human. Four human burials were uncovered by archaeologists at a neighboring site 500 yards away.

"The matter of dating site materials turns out to be difficult for amateurs and is relatively uncertain. It is reasonable to suppose that artifacts found at or near the surface were deposited more recently than those below. For example, one would expect to find fragments of porcelain above artifacts that were deposited before porcelain became available. On the other hand, sites can be disturbed and the materials mixed, particularly to a depth of a foot or so in small local areas. Examination might easily fail to disclose traces of a hole that was made 50 years ago by driving a stake into the ground. Yet a piece of porcelain that accidentally dropped into the hole would come to rest in a layer of materials that had accumulated centuries before porcelain could have found its way to the site. That is why sites are excavated layer by layer and a statistical evaluation is made of the contents of each layer.

"When a site contains charcoal, the possibility exists of dating the layer by the carbon-14 technique [see "The Amateur Scientist," February, 1957]. Our site contained no usable charcoal, however. Only one modern technique of dating was available to us: the hydration method, which is based on the slow corrosion of glassy materials by water. Obsidian and other glassy materials that are moist tend to corrode very slowly through the centuries at a constant rate. Water that is naturally present in the soil diffuses into the noncrystalline structure of the glass and leaches out soda, lime and other substances, thus creating a surface skeleton of silicon. The action is retarded during dry weather. The result of prolonged exposure to varying wet and dry seasons is the growth inward of alternating dark (unleached) and clear (leached) bands roughly analogous to the annual growth rings in trees. The partial reflection of light by the layers sets up optical interference between reflected light waves with the result that the corrosion appears in the iridescent colors observed occasionally in old glass [see "Ancient Glass," by Robert H. Brill; SCIENTIFIC AMERICAN, November, 1963]. The fragile layers tend to flake away when the glass is touched, particularly in man-made glass, and so artifacts to be dated by the hydration method must be handled gently. Technicians select specimens that show little wear and remove slices from facets that appear to be fashioned by man-not from surfaces of natural origin. The slices are ground to thin sections and treated chemically to emphasize the bands. The bands, which vary in thickness from about 20 to 120 millionths of an inch, are then examined under a microscope.

"Amateurs who are skilled in lapidary techniques could doubtless master the hydration method of dating, but we did not attempt it. Instead we submitted 18 specimens of worked obsidian to Harvey Crew of the University of California at Davis for analysis. Two of the specimens were unsuitable for analysis; the remainder indicated ages ranging from 680 to 1,800 years, with the exception of one that indicated 2,900 years.

"A lot of work went into the excavation of Marin-374. At the conclusion of the dig we spent three months compiling data and writing a report that has been distributed to interested archaeologists. Some of the recovered artifacts are now in storage. Others are on display at the Boyd Natural History Museum in San Rafael, Calif., or in the files of the University of California at Berkeley and San Francisco State College, along with copies of our report. When a museum now being considered by the Novato Parks and Recreation Department is completed, most if not all of the items will be on display. Copies of our notes are available on request. We have been invited by David Fredrickson of the department of anthropology at Sonoma State College to participate in the excavation of Marin-27 in Tiburon, Calif., and are now developing plans for a high school class in field methods.

"About 60 percent of Marin-374 was left undisturbed; doubtless it contains more material than we removed. Soon the site will be obliterated by earthmoving machinery, as was a neighboring site, Marin-196. We have recently participated with local archaeologists in a successful campaign for an ordinance forbidding the destruction of sites in Marin County by commercial agencies until a representative sample of artifacts has been unearthed.

"The dig at Marin-374 was a fascinating (if sometimes exhausting) experience, and our club members enjoyed it thoroughly. We feel that our work helped, if only a little, to reconstruct the story of how the Miwok Indians lived during their last 1,500 to 2,000 years.

"There are records of contacts between these Indians and Spanish settlers, but no substantial intermarriage with the Spaniards took place and the line seems to have died out. We have heard, however, that one mixed-blood coastal Miwok still lives in Marin County. We are trying to locate him-or her."

Bibliography

BEGINNING IN ARCHAEOLOGY. Kathleen M. Kenyon. Frederick A. Praeger, 1952.

THE SCIENTIFIC AMERICAN BOOK OF PROJECTS FOR THE AMATEUR SCIENTIST. C. L. Stong. Simon and Schuster, Inc., 1960.

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