Research
Over nearly a century, countless people have studied and scrutinized this mysterious hilltop in Salem, New Hampshire. That work continues today with a league of professional and amateur archaeologists, historians, astronomers, land-surveyors, and many more constantly trying to understand this enigmatic ancient landscape. To date, several distinct layers of history and prehistory have been discovered here. These range from early visitation of this hill as much as 7,000 years ago, to the stone structures themselves which may be 4,000 years old, Woodland Period habitation by local Pawtucket Native Americans, colonial and postcolonial use by the Pattee Family, 19th century logging activity, and early-modern recreational use of the hill.
Prehistory and Ancient History
America's Stonehenge preserves ancient sites dating back more than 4,000 years ago. The materials left behind by these ancient inhabitants range from small stone artifacts, fire pits, and pottery, to the megalithic structures preserved atop Mystery Hill.
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Colonial and Postcolonial Eras
In the early 1700s, Mystery Hill was on the wild frontiers of the Massachusetts Bay Colony. Parts of the property were later purchased by the Pattee Family, who eventually lived here between 1802 and 1850. Their history is fascinating in its own right.
Modern Archaeology
America's Stonehenge was known in local legend for generations, but it was not until 1936 that its archaeological potential was recognized by William Goodwin. For 90 years, archaeological, historical, and other discoveries have been made using the latest methods.
Introduction
Modern research here involves the latest archaeological methods and technology, as well as old-fashioned excavation. This work continues the museum's legacy of involving local professionals and incorporating the most advanced tools into the study of ancient sites. Using Light Detection and Ranging (LiDAR) mapping and Ground Penetrating Radar (GPR) surveys, we continue to discover new and fascinating structures on this site with minimally invasive techniques. The most intriguing structures are selected for excavation and documented. Artifacts recovered during these excavations are preserved, cataloged, and either stored in the museum's archives or selected for exhibition. A curated selection of these artifacts is available to view digitally on the Artifacts page. The structures at America's Stonehenge are the focal point of our work. Chambers, standing stones, and walls across the entire property have been mapped and excavated, with samples being collected for Optically Stimulated Luminescence (OSL) dating at key locations on the site. OLS dating, as well as Radiocarbon-14 dating of contextual materials, the discovery of diagnostic artifacts within the structures, the architecture of the structures themselves, and astrochronological dating of the alignments have all placed the earliest construction of the site at about 4,000 years ago. Many features have been discovered in recent years, including effigy walls, "windows," and other artistic stonework that differentiates this site from the traditional farmers' walls that New England is known for. We do encourage you to visit the site and tour these impressive megalithic ruins for yourself.
Survey Work
Survey work is the first step in archaeological field work, and a significant portion of the ongoing work at America's Stonehenge. With more than 100 acres of ancient structures and living sites, there is still much to discover on this property. Survey work can begin remotely with the use of maps, satellite imagery, and even historical records. This research sets the groundwork for determining historical land-use, property ownership, and the eventual discovery of ancient sites. Following this initial work, field work can be conducted. Site walks are how discoveries are primarily made here at America's Stonehenge. As the name suggests, this involves simply walking through the site and observing the ground, structures, and landscape around you. These site walks can yield brand-new discoveries or, more often, new perspectives on existing structures. During a site walk, taking pictures and documenting ideas is still an important part of the process, as these notes can be referenced later when more formal survey work or excavation is taking place. The advent of modern technologies like LiDAR and GPR has enhanced the survey stage of research, especially at America's Stonehenge. Light Detection and Ranging (LiDAR) is a technology with both commercial and scientific applications. Often used to survey properties for construction and development work, archaeologists quickly adapted the technology to use in the field. LiDAR can be used to accurately map individual structures or entire landscapes; both methods have been used at America's Stonehenge. Tom Elmore of The GeoNAV Group has used handheld LiDAR to map the Main Site, including the interior of the chambers and structures on the site, as well as 15 acres on the top of Mystery Hill. This high-resolution LiDAR imagery has been used to study the intricate details of the structures on the site. Chris Stein of GPI has used the latest drone-mounted LiDAR technology to map the entire 106 acre property. While aerial LiDAR provides a slightly lower resolution image of the structures, this data can be used to survey and discover structures across the entire landscape, particularly structures that may be hidden by the forest itself. Ground Penetrating Radar (GPR) is another commercial technology that has also been applied to archaeological research. GPR uses radio waves to detect subsurface structures, as different materials reflect these waves in different ways. Archaeologists use GPR to map underground structures and locate targets for excavation. At America's Stonehenge, GPR has successfully located many interesting features, including underground drains, wall substructures, and fire pits. Doria Kutrubes of Radar Solutions International has completed much of the GPR work here, including a survey of the Oracle Chamber prior to OSL sample collection, mapping several walls and underground drains, and a survey of areas slated for future excavation.
Excavations
Archaeology is the odd duck of the sciences, but scientific nonetheless. Excavations are inherently disruptive and destructive; the act of observing artifacts removes them from their spatial context and risks irreparably damaging the natural and human environment being studied. For that reason, excavation occurs only in the most extreme circumstances - usually when survey work has identified a particularly intriguing site or the site is at high-risk of unavoidable natural or artificial damage. To mitigate the destructive effects of excavation, modern archaeological techniques emphasize precision and documentation. Excavations continue at America's Stonehenge, though not on the large scale of the early 20th century. Precise excavations target specific sections of the property where the investigation or preservation of the site requires this work. Two main forms of excavation have been used at this site: Shovel Test Pit (STP) studies and Unit excavations. STPs are used to aid non-invasive survey techniques. When an initial survey has identified a section of the property likely to hold artifacts or other important information, an STP study breaks the surface (literally and figuratively). The goal of an STP study is not to recover artifacts, though that does often occur. The primary purpose of an STP study is to create a profile of the site, analyzing the types and concentrations of artifacts, the stratigraphy of the soil, and the location of possible undiscovered features. To accomplish this, a grid of small, 50cm-square pits are excavated at regular intervals, covering a wide area with a limited amount of soil disturbance. STPs have been used to identify a number of features including fire pits, pottery and lithic workshops, historic middens, and even hidden megalithic structures at America's Stonehenge. Artifacts that are recovered during STP studies are still retained, preserved, archived, and displayed as usual. Unit excavations are implemented when previous surveys and STP studies have identified a need to fully uncover a feature and/or collect the artifacts from a particular area. A series of 1m-square pits are excavated, typically side by side, to systematically remove the soil from a large area of the site and completely reveal any artifacts and features below. During unit excavations, rigorous notes are kept to document precisely where artifacts were found in three-dimensional space, as well as information like soil conditions, biological or artificial disturbances, and the presence of features. Photographs and sketches of the units also document the process, mitigating the disruptive nature of these more extensive excavations. In addition to artifacts, excavations can also produce samples that are important for dating the site. Any organic material like wood (including charcoal) and bone can be dated using Radiocarbon-14 Dating, which is discussed at greater length in the next section. Unfortunately, the acidic soils of New Hampshire do not preserve most organic materials very well, but material that has been exposed to fire, particularly charcoal, can be recovered. Most dated samples from America's Stonehenge have come from charcoal, with the exception of a tree root and small bone fragments found on the site, as well as a sample from the dugout canoe that is a part of the museum's collections. Excavations can also identify sections of the site that are candidates for OSL samples, as this dating technique requires a sample to be taken from beneath several inches of undisturbed soil. While soil directly from an excavation cannot be used for this purpose, the wall profile created by an excavation can identify a nearby area where a core sample can be taken for OSL dating.
Dating
Determining the age of stone structures can be difficult, and determining the precise age is nearly impossible, but archaeologists have several tools that can help to narrow down a range of time during which the structures at America's Stonehenge may have been built. Using a combination of diagnostic artifacts, observing the architecture of the structures, analyzing samples for Radiocarbon-14 and OSL dating, and applying astrochronology, researchers have been able to determine that the earliest construction at America's Stonehenge occurred about 4,000 years ago, with several other eras of construction, modification, and habitation occurring after that. Diagnostic artifacts are any artifacts that can be attributed to a specific time and culture. At America's Stonehenge, a variety of diagnostic artifacts have been discovered from a range of cultures and eras. The most recent artifacts date to the time when the Pattee Family lived on the site, from 1802 to 1850, and slightly later when the property was logged. These pieces include 18th and 19th century ceramics, glass, housewares, utensils, metal tools, buttons, clay pipes, and eyeglasses, as well as bricks and other architectural elements of the Pattee house. Artifacts that preceded the colonial and post-colonial use of the site have also been discovered, which include a number of lithic tools and projectile points, as well as early Native American pottery. These items, along with the Indigenous living sites and workshops that were discovered, represent a significant Native American presence on the site between 4,000 and 500 years ago, with a peak between 2,000 and 1,000 years ago. The visible architecture at America's Stonehenge provides a clear distinction between prehistoric and historic stone structures. The megalithic stonework at America's Stonehenge is intricate, bordering on artistic, and rather impractical. Long, winding walls meander all across the property and the low, narrow chambers atop Mystery Hill create a labyrinth of stonework. One chamber could, perhaps, be useful to an early 19th century family for use as a root cellar, but the dozens of chambers and other constructions at America's Stonehenge would have required an immense amount of labor to create, while serving no real purpose to more recent inhabitants. However, the impressive megalithic stonework here would have been a monumental structure for ancient cultures. Megalithic sites are found around the world, including here in North America, and were commonly created by ancient people for ceremonial purposes. The architecture here at America's Stonehenge falls within this category of stonework. Large slabs of stone, astronomically aligned chambers, walls, and standing stones, and a variety of impressive monuments all point to the conclusion that an ancient culture of stonebuilders viewed this site as a temple. Observation is one thing, science is another. Methodologically sound dating techniques have been employed at America's Stonehenge, beginning with Radiocarbon-14 dating. Radiocarbon-14 dating can be used to determine when a living organism died, or more specifically, when it stopped exchanging carbon with the atmosphere. Since organic material is required for this method, Radiocarbon-14 dating cannot be completed on the stone structures themselves. However, organic samples discovered in context with the structures can be dated, and these samples have yielded some impressive results. With the 19th century occupation of the site and later use as a recreational area, there have been some modern samples of charcoal found on the site, especially in the area around where the Pattee house once stood. Charcoal was also discovered in several stone chambers, however, that was dated to significantly older ages. Samples of charcoal found on the site have been dated to between 2,000 and 4,000 years ago, indicating not only that there was a human presence on this site thousands of years ago, but that the structures were here at that time as well. Other samples of charcoal have been dated from excavations outside of the site, including at living sites and workshops, which were dated to the Woodland Period when the Pawtucket tribe lived in this region. In 2020, a new method of dating archaeological sites was brought to America's Stonehenge. Optically Stimulated Luminescence (OSL) is a method of dating inorganic material, particularly samples of soil and rock. This method returns a minimum age of the structure, telling researchers the last time that the sample had been exposed to the radiation that comes from direct sunlight. This means that the structures themselves could be accurately dated, rather than relying on artifacts or samples found in context with the structures. Dr. James Feathers, working with the New England Antiquities Research Association (NEARA), collected samples from America's Stonehenge in September of 2020. One sample, collected from the soil on top of the Oracle Chamber, returned a date of 1550 CE. This means that the soil, which could only begin to accumulate after the chamber had been completed, had been undisturbed for at least 500 years. Another sample taken from the wall outside of the Watch House Chamber was slightly older, measuring 1400 CE. This wall was in place long before permanent European colonization in New England - and at least 92 years before Christopher Columbus' fateful voyage. Whether the soil was deposited all at once in 1400, or took several centuries to accumulate is still up for debate, but the stratigraphy of this site seems to indicate the latter. OSL dating is an incredible new tool that archaeologists can use to prove, undoubtedly, that many of New England's rock structures have precolonial origins. For more information on OSL dating at stone sites in the Northeast, read Dr. Feathers' article, published November 2022. A distinctive feature of America's Stonehenge is its function as an astronomical calendar and observatory. Astronomical alignments at the site observe the rising and setting of the sun, moon, and some stars. Due to the earth's axial precession, the azimuths of these celestial bodies change over time. The astronomical alignments at America's Stonehenge were surveyed throughout the 1960s and 1970s, and the data sent to the Harvard Smithsonian Center for Astrophysics. There, Dr. Shoshana Rosenthal, a leading expert on archaeoastronomy who had worked on the calculations for Stonehenge in the UK, determined that the alignments at America's Stonehenge would have worked approximately 4,000 years ago.
Archaeoastronomy
The use of America's Stonehenge as an astronomical observatory was first theorized in the early years of the museum. The site's location atop a prominent hill makes it a prime location to observe celestial bodies, and the standing stones that surround the main complex of structures are reminiscent of astronomically significant sites around the world. The first attempts to clear paths to these standing stones and to survey the property were made in the 1960s. The first alignment to be observed was the Winter Solstice Sunset. Since then, 57 theorized alignments with the sun, moon, and stars have been discovered on the site, and many more may be possible. Solar alignments at this site occur on an annual cycle. There are standing stones and monuments which mark the rising and setting of the sun on the Winter Solstice, Summer Solstice, and Spring and Fall Equinox. The cross-quarter days are also represented with monuments on this site, marking the mid-points between solstices and equinoxes. These days were prominent holidays for ancient cultures around the world, and many people continue to celebrate them today whether they know it or not! Halloween, for instance, is the modern interpretation of the ancient holiday Samhain, which falls on the cross-quarter day after the Fall Equinox and before the Winter Solstice. Lunar alignments have also been found on this site. The moon travels on a unique course through the night sky, and does not move on an annual cycle. Rather, the moon's position on the horizon changes over a cycle that lasts 18.6 years. During the Lunar Major cycle, the moon will rise and set at northerly and southerly extremes that are beyond the annual extremes of the sun. 9.3 years later, during the Lunar Minor cycle, the moon's extreme points on the horizon will fall within the sun's extremes. Ancient sites around the world observed these cyclical movements of the moon, including the builders of America's Stonehenge. Monuments were built marking the points where the moon will rise and set during both the Major and Minor cycles. Stellar alignments are also a prominent feature at America's Stonehenge, particularly the alignment with the Pole Star. The North Stone is a monolith that points toward true north, the point in the sky where the Pole Star remains throughout the night. Many walls and chambers on the site are also aligned with true north, indicating that the builders of this site appreciated the significance of this cardinal direction. While we are taught that the North Star never moves, the North Star does in fact change over thousands of years. Again, due to the earth's precession, the North Pole points toward different stars over a cycle that lasts more than 26,000 years. Today, the Pole Star is Polaris, found in the constellation Ursa Minor. 4,000 years ago, the pole star was Thuban, a central star in the constellation Draco. The builders of this site would have watched Draco spin around the Pole Star, perhaps contributing to the significance of serpent symbolism found at this site. The astronomical significance of this site is also evident in the Watch House Chamber, where a quartzite stone built into the rear of the structure is illuminated on the morning of the Spring and Fall Equinoxes. Illuminations, and the use of natural shadow and light to accent ancient architecture is a practice found around the world. A well-known example of this style of astronomical architecture is found at Newgrange, an ancient passage tomb in Ireland, where the sunlight of the Winter Solstice illuminates the interior of the chamber.
Preservation
Preserving the site for future generations is a key component of the ongoing research at America's Stonehenge. To mitigate the impact of natural damage to the site, a forestry project was completed over the last several years to thin the forest and remove potentially damaging trees from around the structures. A healthy, biodiverse forest now surrounds the site and there is a reduced risk of trees falling on or otherwise damaging the stone structures. To further mitigate damage to the site from other natural and artificial sources, museum staff work tirelessly to keep trails well-maintained and keep the site clean of brush, litter, and other debris. In addition to physically preserving the site, we are also constantly working to update our records, files, and collections. Efforts to digitize the museum's archives and collections are underway, the results of which can be accessed on the Artifacts page.
Theories and Conclusions
Unfortunately, the original builders of America's Stonehenge remain unknown. While we do know that early construction happened here about 4,000 years ago, no diagnostic artifacts from that time have been discovered. The earliest diagnostic artifacts, attributed to the Pawtucket people, are dated to about 2,000 years ago. Similarities to megalithic structures in Europe, as well as the discovery of possible Old World inscriptions, has led some researchers to believe that there may be a connection between this site and ancient Western European or Mediterranean cultures. In the ongoing research of this site, we strive to keep an open mind. Before forming any conclusions about the origins of this site, it is important to follow where the evidence leads. Hopefully, with continued study, we can reveal who actually built these structures and what culture or cultures used the site over its thousands of years of history.