Hidden History Found Beneath Alcatraz


Scientists say there’s much more to “the Rock” than crime and punishment, and they have come to Alcatraz to investigate the hidden history that lies beneath the prison walls. (BBC)

Use our resources to appreciate how archaeologists are using futuristic technology to understand the distant past.

Some of the most coveted real-estate in America? Photograph by David Corby, courtesy Wikimedia. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Click to enlarge!! This is a beautiful panorama of Alcatraz Federal Penitentiary, now part of the National Parks Service.
Photograph by David Corby, courtesy Wikimedia. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Discussion Ideas

  • Alcatraz Island was home to one of the most infamous prisons in the United States. Some of the most notorious inmates detained at Alcatraz Federal Penitentiary include Chicago wiseguy Al Capone, Boston mobster James “Whitey” Bulger, Los Angeles criminal leader Meyer “Mickey” Cohen, and bank robber George Celino Barnes—better known as “Machine Gun Kelly,” who mostly operated in the South. Why do you think Alcatraz housed criminals from all over the U.S.?
    • It’s all in the name—Alcatraz was a federal penitentiary, not a state or local facility. In fact, prisoners were not sentenced to Alcatraz at all. The facility housed prisoners who consistently caused trouble at other federal penitentiaries. Today, the most high-security prisoners in the United States are held at so-called “Supermax” prisons. There is only one federal Supermax prison, located in Florence, Arizona. This facility houses such criminals as 9/11 conspirator Zacarias Moussaoui, “Unabomber” Theodore Kaczynski, and FBI spy Robert Hanssen.


  • The archaeologists profiled in the BBC article on Alcatraz are using ground-penetrating radar to identify a military fortress buried beneath the prison. Read through our case studies of the archaeology being done at sites much, much older than Alcatraz—Tell es-Safi and Tel Kabri, both in what is today Israel. What technologies are they using might be of interest to the Alcatraz archaeologists? What technologies do you think would not be useful?
    • The Alcatraz study actually sounds similar to the initial Tel Kabri study, where ground-penetrating radar helped archaeologists identify a site of interest. The Multi-Frequency Domain Electromagnetic (MFDEM) now being used at Tel Kabri surveys specific underground layers. This technology might help archaeologists at Alcatraz by allowing them to skip some sections of site to focus on others.
    • The molecular-level technology used by archaeologists at Tell es-Safi is probably too granular to be of much use to the Alcatraz team right now. That technology, including two types of spectrometers, analyzes material at the atomic level. That is very useful at an ancient site like Tell es-Safi, where molecular changes in the soil could reveal an undiscovered and undocumented history. At Alcatraz, at least at this stage of this archaeological project, it’s probably too specific.


  • In archaeological terms, the fortress being studied at Alcatraz is actually not that old! It dates only from the 19th century. Why do you think preserving artifacts and features from the fort has been so difficult? Read through our short section on “Where to Dig” in our encyclopedic entry on archaeology, and take a look at our photo of the Leshan Giant Buddha for some clues.
    • Inhabited areas, even isolated places like Alcatraz Island, tend to be built in layers. Archaeologists have to penetrate the current layer (the remains of the federal prison) to get to the features below. The encyclopedic entry gives the example of a dig in Rome, Italy: “Archaeologists looking for an ancient Roman fortress, for instance, may have to first excavate a Renaissance bakery and medieval hospital.”
    • Alcatraz Island sits in the middle of San Francisco Bay. San Francisco Bay connects to the Pacific Ocean. The archaeologist in the BBC article explains the deteriorating process of weathering: “As soon as you are in this misty, wet environment with the salt air, the salt gets in with the water and the oxygen and causes corrosion. And then that produces cracks on the concrete. And once that begins, the deterioration happens very quickly.”


  • What archaeological artifacts and features do you think might exist below the 19th-century fortress?
    • The Spanish were the first Europeans to colonize the island, so maybe the remains of a Spanish fort, residence, or church?
    • The Ohlone, a Native American people, are indigenous to the San Francisco Bay Area, including Alcatraz Island. Although there is little evidence the Ohlone inhabited Alcatraz itself, archaeologists may yet find shell mounds or other features buried deep below “The Rock.”

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