Located just west of Monks Mound is Mound 39, a small, rounded mound. Originally it was probably rectangular; that is how it is illustrated on the Patrick Map of 1876. A straight line can be drawn from the supposed north edge of Mound 39 to the north boundary of Monks Mound. Both the McAdams Map and the earlier Thomas Map show a mound in a slightly different location than this, but they probably refer to Mound 39. The latter two maps were just sketch maps of the site, and their locations for Mound 39 should not be taken as seriously as the Patrick Map. The USGS map confirms the location of this mound as it appears on the Patrick Map, as does the 1966 UWM Map.
There is some question as to the original size of Mound 39. The Patrick Map suggests that it was a large, flat-topped platform mound equal in size to Mound 41. The other maps show it to be somewhat smaller. Moorehead’s map suggests the north-south and east-west dimensions were both about 240 feet (173.15 meters). The 1966 UWM Map shows an east-west dimension of approximately 48 meters (157.5 feet) and a north-south dimension of approximately 42 meters (137.8 feet).
Thomas gives the height of this mound as 10 feet (3.05 meters). The later surveys suggest that on the north side, toward the slope of the bank of Cahokia Creek, the mound had a height of around 19 feet (5.8 meters) and on the south side a height of 7 to 8 feet (2.1 to 2.4 meters). The overall average height of this mound on the UWM Map is 1.1 meters (3.6 feet).
The data suggest that the considerable alteration of the shape of this mound is probably due to modern construction and agricultural practices. The height data also conform to the changes in form suggested by comparing the Patrick Map illustration of Mound 39 with its appearance on the 1966 UWM Map.
The alteration may be partly due to the sawmill located on this mound in the 1800s; it is often called the Sawmill Mound. Moorehead reports that in the period 1850-1860 an explosion in the sawmill killed several workmen. They were apparently buried in one of the nearby mounds, possibly Mound 73 or Mound 47 (Moorehead 1929:39). As Moorehead suggests, that should be kept in mind should future archaeologists find skeletons with traces of wood coffins about them.
The only excavations into this mound were conducted by Moorehead in the early 1920s. His reports do not include any maps of those excavations because material was too irregularly distributed in the mound, he said, to make a map worthwhile. His reports did include the following (Moorehead 1929: 38-40):
- Eight burials accompanied by some grave goods were located along the southern slope of the mound.
- No burials were found in a 35-foot-long (10.7 meters), 5-foot-deep (1.5 meters) trench dug along the east side.
- A center pit 14 by 15 feet (4.3 by 4.6 meters) wide and 16 feet (4.9 meters) deep was dug into the mound.
An auger was used to probe an additional 3.5 to 4 feet (1.1 to 1.2 meters) to a base of heavy, wet clay. That probing revealed that:
- The mound was stratified, with strongly marked series of alternating bands of dark earth and yellow earth. The dark bands were 3 to 10 inches (7.6 to 25.4 centimeters) wide and the yellow bands were 12 to 24 inches (30.5 to 61 centimeters) wide.
- The layers were not even. A conically formed deposit in the northwest corner dipped from the east to the southeast, whereas, according to Moorehead, 10 feet (3.05 meters) down the layers appeared to be more horizontal. It is possible that this formation represented a slope of an earlier construction stage.
- A heavy black layer was found on the south side of the trench and auger borings on the south side of the pit showed a heavy blue clay mixed with a grayish clay. A heavy blue clay, the natural deposit just below the soil development horizon, has been found by more recent excavators throughout much of the site area. This may just be another indication that heavy blue clay is universal throughout the Cahokia site area.
- Scattered throughout the mound were bits of pottery fragments, chips, spawls, a ceramic mammal-head effigy, an awl from a deer jaw, and a human head effigy cut from a freshwater mussel shell.
- Moorehead’s workmen found a number of disturbed burials, but no indication is given of their location. These were apparently scattered throughout the area. Since the soil was soft and disturbed, Moorehead assumed the burials were in an area where either Patrick or McAdams had dug.
- Moorehead thought that extensive habitation areas once surrounded this mound. Black pottery predominated, but a few fragments of red pottery were also found.
- Furthermore, it was Moorehead’s interpretation that a long, low platform existed between Mounds 39 and 77 directly to the south (Moorehead 1929: 38-41).
Skeleton No. 11, in Moorehead’s terminology, was the most extensively described and illustrated of the burials found in Mound 39. It was an extended burial with the head to the northeast (Moorehead 1929: Plate xxix, Figure 2) and apparently was well preserved; there were two ceramic vessels near the right hand, and another bowl near the left knee. A shell gorget and a bone knife were also found with this skeleton.
Mound 39 appears to have been a platform mound, though indication of earlier building stages are present. Several burials were noted throughout the fill, but their position within the mound structure is not documented sufficiently to indicate their nature.