Poverty Point

Poverty Point is a prehistoric earthwork built by the Poverty Point culture in present-day northeastern Louisiana. The site lies 15.5 miles (24.9 km) from the current flow of the Mississippi River, on the edge of Macon Ridge. It is a state historic site, a U.S. National Monument, a National Historic Landmark and a UNESCO World Heritage Site. The earthworks are named after Poverty Point Plantation, a 19th-century slave plantation on the property.

The earthen ridges and mounds were built by indigenous people between 1700 and 1100 BCE, during the Late Archaic period. The 402-acre (163 ha) property is described as the largest and most complex Late Archaic earthwork occupation and ceremonial site yet found in North America. Archaeologists have proposed that it served as a settlement, a trading center, a ceremonial religious complex, or some combination of these.

The core of the site measures about 345 acres (140 ha), although the total occupation area extended for more than three miles (5 km) along the Bayou Macon. The main feature is six concentric, C-shaped ridges, separated by swales and divided by four aisles. The outside ridge has a diameter of about three-quarters of a mile (1.2 km) and the innermost about three-eighths of a mile (0.6 km). The scale is so massive that the geometric design was recognized only when researchers examined aerial photographs. Radiocarbon dates suggest most ridges were built between 1600 and 1300 BCE.

The innermost ridge and the edge of Macon Ridge enclose a 37.5-acre (17.4 ha) plaza. It looks naturally flat but was extensively modified, with gullies filled and soil added to raise the ground by as much as 3.3 ft (1 m) in places. Excavations found huge wooden posts, and later geophysical survey identified circular features from about 82 ft (25 m) to 206 ft (63 m) in diameter, which proved to be rings of wood posts built while the earthworks were under construction.

The largest mound, Mound A, stands 72 ft (22 m) tall at its highest point and measures about 705 x 660 ft (215 x 200 m) at its base. It lies west of the ridges and is roughly T-shaped from above. Some have interpreted it as a bird, or as an Earth island representing the cosmological center of the site. Euroamericans described the site in the 19th century, and professional excavations have focused on it since the 1950s.

The monumental earthworks of Poverty Point consist of a series of earthen ridges, earthen mounds, and a central plaza. The earthworks core of the site measures about 345 acres (140 ha), although archaeological investigations have shown that the total occupation area extended for more than three miles (5 km) along the Bayou Macon. The earthworks include six concentric, C-shaped ridges that extend to the edge of the Macon Ridge and several mounds outside and inside of the earthen ridges. These concentric ridges are unique to Poverty Point.

Six C-shaped ridges

The main part of the monument is the six concentric C-shaped ridges. Each ridge is separated from the next by a swale or gulley. The ridges are divided by four aisles forming earthwork sectors. Three additional linear ridges or causeways connect earthen features in the southern half of the ridges. Today the ridges vary from 0.3 to 6 ft (10 –185 cm) in height relative to the adjacent swales. Archaeologists believe they were once higher in places, but have been worn down through roughly 150 years of agricultural plowing. The slightly rounded crest of each ridge varies from 50 – 80 ft (15–25 m) in width. The width of the intervening swales is 65 – 100 ft (20 – 30 m). The approximate diameter of the outside ridge is three-quarters of a mile (1.2 km), while the innermost ridge's diameter is about three-eighths of a mile (0.6 km). The scale of the ridges is so massive that it wasn't until researchers examined aerial photographs that they were able to recognize the geometric design. Radiocarbon dates suggest that most of the ridges were constructed between 1600 and 1300 BCE.

Plaza

Enclosed by the innermost concentric ridge and the eastern edge of Macon Ridge is a large, 37.5-acre (17.4 ha), plaza. Although the plaza appears to be a naturally flat area, it has been modified extensively. In addition to filled gullies, archaeologists found that soil was added to raise the level of the ground surface in some areas by as much as 3.3 ft (1 m). In the 1970s, excavations revealed evidence of huge wooden posts in the western plaza. Later geophysical survey identified several complex circular magnetic features, ranging from about 82 ft (25 m) to 206 ft (63 m) in diameter, in the southern half of the plaza. Based on the geophysical data, archaeologists with the University of Louisiana at Monroe and Mississippi State University undertook targeted excavations of some of the circular magnetic features; they found large post pits, indicating the magnetic circles were rings of wood posts. Radiocarbon dates from the post pit fill and from overlying features indicate the post circles were part of the landscape built by Native Americans, even as the earthworks were under construction.

Mound A

The earthen mounds are the most visible earthworks at the site. The largest of these, Mound A, is 72 ft (22 m) tall at its highest point and about 705 x 660 ft (215 x 200 m) at its base. Mound A is located to the west of the ridges, and is roughly T-shaped when viewed from above. Some have interpreted Mound A as being in the shape of a bird or as an "Earth island" representing the cosmological center of the site.

Researchers have learned that Mound A was constructed quickly, probably over a period of less than three months. Prior to construction, the vegetation covering the area of Mound A was burned. According to radiocarbon analysis, this burning occurred between 1450 and 1250 BCE. The prehistoric builders immediately covered the burnt area with a layer of silt, followed quickly by the main construction effort. There are no signs of construction phases or weathering of the mound fill even at microscopic levels, indicating that construction proceeded in a single massive effort over a short period. In total volume, Mound A is made up of approximately 8,400,000 cubic feet (238,000 cubic meters) of fill, making it the second-largest earthen mound (by volume) in eastern North America. It is second in overall size to the later Mississippian-culture Monks Mound at Cahokia, built beginning about 950-1000 CE in present-day Illinois near the Mississippi River.

Shallow borrow pits are located near Mound A. Presumably the Poverty Point people carried dirt from those borrow pits and from elsewhere on the site to build the mound.

Mound B

Mound B is located north and west of the six concentric ridges and 2050 ft (625 m) north of Mound A. The mound is roughly conical in form and is approximately 21 ft (6.5 m) in height with a 180 ft (55 m) basal diameter. Dating to sometime after 1700 BCE, Mound B was the first earthwork built at Poverty Point. Built in several stages, charcoal, fire pits, and possible postmolds were found at various levels within the mound. The impressions of woven baskets were preserved in the fill of an upper level of the mound construction. The final stage of the mound construction was a conical silt loam lens that covered the entire mound surface. During excavations in the mid-1950s, a human bone was reported within an ash lens at the base of the mound. At the time, this finding was reported as evidence of a cremation. However, recent research failed to find any evidence of the ash lens. Researchers suggest instead the reported lens represents a fine gray silt common to E horizon soils on the Macon Ridge and often found beneath mounds. The identification of the bone (reported as the proximal end of an infant's femur) has also been disputed and is not curated in any known collection from the site.

Mound C

Mound C is located inside the plaza area near the eastern edge of Macon Ridge. Mound C is 6.5 ft (2 m) in height, about 260 ft (80 m) long, and today is 80 ft (25 m) wide. The width is truncated by erosion along the eastern edge. There is a depression that divides the mound, which is thought to have been created by a 19th-century wagon road which proceeded northward to the old town of Floyd, Louisiana. Multiple radiocarbon dates for Mound C bracket the entire occupation of the site, but one radiocarbon test result from beneath the base of the mound suggests Mound C is one of the earliest constructions at the site. Mound C is composed of several thin layers of distinct soils with small amounts of accumulated debris, or midden, between them, indicating they were added over time. The uppermost level gave the mound its final dome shape.

Mound D

Mound D is a rectangular earthwork having a flat summit that today contains a historic cemetery associated with the Poverty Point Plantation. This mound is about 4 ft (1.2 m) tall and 100 x 130 ft (30 x 40 m) at its base and is situated on one of the concentric ridges. Several lines of evidence suggest that Mound D was built, at least in part, by the Coles Creek culture nearly 2000 years after the Poverty Point culture occupation of the site. First, Coles Creek culture ceramics were recovered near Mound D. Second, Coles Creek culture ceramics were recovered 40 cm below the ground surface near Mound D. Third, optically stimulated luminescence analyses on soils beneath and within the mound, which determine the date the soils were last exposed to sunlight, are consistent with a Coles Creek culture mound constructed on top of a Poverty Point ridge. The mound is also known as Sarah's Mound because Sarah Guier was buried in the mound.

Mound E

Mound E is sometimes referred to as the Ballcourt Mound. The Ballcourt designation comes from "two shallow depressions on its flattened top which reminded some archaeologists of playing areas in front of outdoor basketball goals, not because of any suggestion of actual activities at Poverty Point."

Mound E is located 1330 ft (405 m) south of Mound A and is a rectangular flat-topped structure with rounded corners and a ramp extending from the northeast corner. Mound E is 13.4 ft (4 m) in height and 360 x 295 ft (110 x 90 m) at its base. The profile of an excavation unit on the edge of Mound E revealed five construction stages that were corroborated by series of soil cores recovered across the mound surface. No features were recorded in the excavations and only a small number of artifacts were recovered. Several of the recovered artifacts were of nonlocal chert, such as novaculite, characteristic of the Poverty Point site raw material assemblage. Until recently, dating of Mound E relied on a similarity with the construction of Mound B and their relatively similar soil development. In 2017, a small piece of charcoal was recovered in a soil core taken from the base of the mound ramp. This charcoal, from the base of the mound, provided a radiocarbon date suggesting construction sometime after 1500 BCE.

Mound F

A sixth mound was discovered at Poverty Point in 2013. Known as Mound F, it is located outside and to the northeast of the concentric ridges. Mound F is about 5 ft (1.5 m) tall and 80 x 100 ft (24 by 30 m) at its base. A radiocarbon date on charred wood from the mound base indicates it was built sometime after ca 1280 BCE, making it the last Archaic mound added to Poverty Point.

Lower Jackson and Motley mounds

Approximately 1.8 miles (2.9 km) south of the Poverty Point site center is the Lower Jackson Mound (16WC10) a conical structure 10 ft (3 m) in height and 115 ft (35 m) in diameter at its base. For many years, archaeologists believed the Lower Jackson Mound was built during the same time as the Poverty Point site. However, modern radiocarbon dates from the base of the Mound demonstrate that the Lower Jackson Mound was built ca. 3900 to 3600 BC which predates the Poverty Point earthworks by about 1500 years. Artifacts typical of the early date, such as baked loess blocks and Evans projectile points, were recovered near the mound. Lower Jackson Mound is on the same north–south line as the later Poverty Point Mounds E, A, and B.

Approximately 1.2 miles (2.2 km) to the north of the Poverty Point earthworks is the Motley Mound (16WC7), which is 52 ft (16 m) in height with a base that measures 560 x 410 ft (170 x 125 m). Motley Mound has some similarity in form to Mound A, however, the cultural affiliation of this earthwork remains speculative.