Pocket Guide for Identifying Artifacts in Yosemite National Park

Archeologist at an excavation site near Lembert Dome in 2023.

 

This guide is available to help visitors, volunteers, and employees protect historic resources and our cultural heritage. Thank you for your help!

 

 

Know the Law

Anything more than 50 years old is historic and should be left in place for archeological research. In a national park, it is illegal to damage, deface, or remove archeological objects.

Archeologists map and study things made, modified, and transported by humans to piece together the stories of human history that may not be in the written record. Studies of historic material (typically over 50 years old) can answer research questions about culture, demographics, settlement, travel, trade, and other human activities.

 

Trash: Pick it up

• Plastic Objects

• Rubber

• Cigarette butts

• Paper

• Aluminum cans with pop tops

• Diapers and toilet paper

• Plastic and cellophane wrappers

• Concrete and asphalt (only pick up if it can be done without causing any ground disturbance).

Historic: Leave it alone

• Purple or aqua glass bottles or bottle fragments

• Very thick or distorted glass

• Rusted metal objects (cans, nails, scrap metal, railroad spikes, etc.)

• Non-plastic buttons

• Ceramics

• Horseshoes

• Decayed leather

• Bones

• Obsidian

• Pull-tabs and pull-tab cans

When in doubt, contact a ranger or the Yosemite archeology office: 209/379-1314.

 

Historic Glass Bottles

DON’T COLLECT: Glass bottles that look old, have interesting colors like blue, cobalt, purple, or milky white. Do not collect bottles that are thick and uneven, have bubbles in the material, or if there are bumped letters on the surface.

DO COLLECT: Modern beer bottles, modern jars, and other objects that you see in stores.

Pontil Scar

Bottle bases with a circular scar and no embossed information, may have been mouth-blown without a mold sometime before 1860.

Color

Bottles with an amethyst or purple tint contain manganese dioxide which was used in glass making between 1880 and 1917 and causes glass to change color in the sun.

Aqua-colored glass was made with sand containing iron and can be dated between 1800 and 1920.

Truly colorless glass first appeared in 1930.

Lip or Finish

Bottles with applied lip finishes may date between 1840 and 1885. The side mold seam often ends somewhere on the neck of the bottle and the lip is irregularly shaped.

If a thin side mold seam continues through the entire lip of the bottle, it was likely machine-made after the 1920s.

Bubbles

Many bubbles in the glass can mean that the bottle dates before 1910 when machine-manufacturing and materials improved.

 

From left to right: aqua bottle, thick, uneven glass; cobalt medicine bottle, embossed lettering; amber bottle, embossed lettering, thick walls; very small medicine bottles, thick glass, and embossed letters; and insulator for power line, thick aqua glass with embossed lettering.

 

Historic Metal and Cans

DON’T COLLECT: Very rusty cans, cans without openings you recognize, or anything that looks very old.

DO COLLECT: Aluminum cans with pop tops.

Can scatters are very common archeological sites throughout Yosemite. They can indicate the location of road, trail, or mining camps. The size of the can scatter can indicate the size of the work crew and the length of time they spent at the camp.

Lid Closure

1810–1930: Hole-in-cap cans with soldered venting hole and cap on lid hole

Cans made entirely by machine with machine-made lids that are one piece were made after 1904.

Seams

If the seam on the side of the can was soldered with lead it probably dates before the 1890s.

If the seam is crimped or double-locking using no solder, it was machine-made after the 1890s.

Opening

Church-key opened beer and soda cans date between the 1930s and 1960s.

Pull-tab openings were first made in 1962.

Aluminum cans were introduced in the 1950s and modern pop-top cans first appeared in the 1980s.

Reference

HOW OLD IS "OLD"? Recognizing Historical Sites and Artifacts by Sharon A. Waechter Far Western Anthropological Research Group, Inc., 2007.

 

From left to right: Old Canada Dry can, rusty, faded printed label, church key opening; broken can, rusty, fragmented (most commonly found); square nails, rusty, square heads, irregular (used in old cabins).

 

Historic Ceramics

DON’T COLLECT: Anything made from ceramics; all ceramics are important to the park.

Ceramic material is often found in concessioner and government dump sites in Yosemite prior to the environmental ethic that began in the 1970s. Dishware can be used for decades before it is thrown out.

 

From left to right: ceramic bottle, whole; ceramic bottle, fragmented.

Maker's Marks

Identifying marks on the bottoms of dishware tended to change over time. A particular mark can indicate when and where the dish was made. The most common historic dishware found in Yosemite was made in the US or England. Some are listed below.

Design

Victorian monochrome floral, wreath, and scroll designs represent some of the oldest ceramics found in the Yosemite area. These ceramics were made prior to 1890 and are associated with wealthier people.

The growing middle class in California during the 1850s–1890s comprised a large market for cheaper British vitreous or vitrified ironstone with molded relief patterns.

The Art Nouveau style combined geometric and botanical elements. It was popular from the 1890s to about 1910.

Naturalistic multi-color floral designs ascended in popularity during the early 1900s.

Simple geometric designs also date to the early 1900s when American culture rejected the perceived excesses of Victorian design. This style continues to be popular today.

 

From left to right: broken plate, painted designs; old mug, painted designs; ceramic shard, fragmented piece (most commonly found).

 

Bones

DON’T COLLECT: Any bones. All bones must be left in place (do not touch or move).

 

Bone fragments.

 

Obsidian

DON’T COLLECT: Any obsidian. All obsidian within the park are artifacts. Obsidian projectile points/arrowheads, come in a large variety of shapes and sizes. It is very important to not move or touch these objects. Obsidian can easily be mistaken as dark glass shards.

 

From left to right: Obsidian shards, fragmented, black and shiny on one side or more; obsidian core, large chunk of obsidian with small pieces knocked off it; obsidian project points in varying sizes.

 

If you find an artifact, you will feel immediately connected to the continuum of human history in Yosemite! Please look, but don't touch. If artifacts are moved even a few feet, we can lose valuable contextual information. You may take photos of artifacts that you find within the park, but please keep all locational information to yourself if you decide to post pictures on social media.

If possible, please record the location and take a picture (if you know how, take a GPS coordinate of where you found it). Let Yosemite National Park know about an object by emailing us.

Learn more about archeological work in Yosemite.