Yet, somewhat earlier the artificial nature of the mound was questioned:
But it is now seriously questioned whether these mounds are the work of art. I know not that any writer ever ventured to attack this supposition until John Russell, esq. sent forth his essay in the Illinois magazine, of March, 1831. Mr. Russell is a citizen of this state, and well-known as a writer of considerable talents and literary acquirements. He has had opportunity of examining for himself, many of those mounds, of various dimensions. He maintains they are not artificial, and offers objections to their being productions of human art, not easily obviated. [Peck 1834: 54]
And in 1873, the local history of Madison County, Illinois, stated the following:
Along the southern border of the county the Canteen Mounds, large, natural formations occur. The origin of these remarkable phenomenon of nature has excited much comment among our best minds, many attributing the mounds to artificial origin. The most prominent of these formations is Monks Mound. [Illustrated Encyclopedia and Atlas of Madtson County 1873: 9]
Those who proposed Monks Mound was a natural phenomenon were probably influenced by racist attitudes. Many believed that the ancestors of the American Indian did not have the capacity to apply themselves to any task as time consuming and elaborate as the building of Monks Mound. (See, for example the description given by John Francis Snyder of the northwest section of Monks Mound quoted above.) Consequently, popular opinion either declared the mounds to be of natural origin or built by some pre-Indian race of mound builders (Silverberg 1968). In 1915, Dr. A. R. Crook, a geologist and director of the Illinois State Museum, is quoted by Moorehead:
Chemical and mineralogical study of the soil, as well as paleontological and physiographical investigations, indicate that the mounds are the remnants of the glacial and alluvial deposits which at one time filled the valley of the Mississippi River and this region. It may be well to inquire if all so-called mounds in the Mississippi Valley are not natural topographic forms. [Moorehead 1929: 115; Crook 1915: 74-75]
Another geologist earlier suggested that the mounds, and particularly Monks Mound, were of natural origin but had artificial constructions placed on the natural features:
To a height of 35 feet above its base the material of Monks Mound shows assortment and stratification, which is evidently natural. Above that height it affords no structural evidence bearing on the question whether it is of natural or artificial origin; but the form plainly indicates the work of man, and not of geological processes. It is highly probable that the mound in its natural condition was much lower and broader than at the present, and was a rounded, almost drumloidal form, similar to the smaller ones of the group which now surround it. By cutting down its margin to the level of the surrounding plain its builders obtained | material to raise the mound to perhaps two or three times its former height without making excavations beneath the level of the plain and without carrying material from the bluffs, 2Uz miles distant. There is no evidence that material was obtained by either of these latter means. [Fenneman 1911: 12]
Crook changed his mind after observing archaeological excavations into the mounds, viewing the core borings done by M. M. Leighton (a geologist) and Moorehead, and examining aerial photographs from the U. S. Army Air Service taken by Lt. Goddard (Goddard 1969; Hall 1968; Fowler 1977).
The debate, though, was finally settled by archaeological excavation. The first of these excavations, although not carefully controlled, was conducted by the property owner, Mr. Rameyin the late 1800s. McAdams described Ramey's excavation in bi8 1883 publication:
About midway, on the north side, or face of the pyramid, and elevated 25 or 30 feet above the base, in a small depression, stands a pine tree, singularly enough, since this tree is not found in the forests in this locality. There was a story rife among the early settlers that this tree stood at the mouth of an opening or gallery into the interior of the mounds. To ascertain the truth of this matter, Mr. Thomas Ramey, the present owner of the mound, commenced a tunnel at this tree and excavated about ninety (90) feet towards the center of the mound. When fifteen feet from the entrance to the tunnel a piece of lead ore was discovered but no other object of interest was found. The deposits penetrated by the tunnel are very plainly shown to be the same as seen in the cellar mentioned above. [McAdams 1883: 2-3]
McAdams had previously commented that the excavations on the third terrace revealed black "cumulus" or mold interspersed with yellow clay, sand, or marly loess. It is interesting to compare his statement with Dr. J. F. Snyder's, written about 20 years after the event; Snyder reported that he detected nothing but "solid bluff clay."
Several years ago its proprietor, Hon. Thomas T. Ramey, dug a tunnel 90 feet in length in direction of its center, on the north side, about 30 feet above the base. In that exploration a small cube of lead ore was discovered, but no charcoal or ashes; nor a flint, pot sherd or bone was found to indicate that the solid bluff clay excavated had ever previously been disturbed. But in that clay taken out of the tunnel I afterwards detected and secured several specimens of small semifossil fluvialtial shells, often occurring in the drift deposits of the bluffs . . . In the same drift deposits fragments of galena are not uncommon. [Snyder 1909: 90-91]
Because of the enormous volume of earth in this "stupendous pile of dirt," elaborate excavations and tunneling have been discouraged. The Ramey family did not permit such excavations to take place. After the turn of the century, occasional probes attempted to determine the mound's structure and content to decide the question of its natural or artificial origin. This was certainly an issue when the mounds area was proposed for a state park. Dr. A. R. Crook (mentioned above) made 25 borings in the north face of the mound. Warren K. Moorehead and M. M. Leighton, in the 1922 season, also made auger borings on the north end Ñ three on the summit and two on the east slope. Pits were dug 3 feet (0.9 meters) deep and auger bored to a depth of 17.5 feet (5.3 meters), assuring penetration to a depth of more than 20 feet (6.1 meters). Unlike Crook, Moorehead felt the auger borings definitely showed the mound to be man-made. Crook, as mentioned earlier, later came to accept this interpretation. No other excavations were conducted on Monks Mound until the 1960s when Washington University sponsored excavations on the fourth terrace, and, in 1965 and 1966, a solid-core drilling technique was employed to determine the nature of Monks Mound's construction. In all, nine holes were cored, one on the first terrace, one on the second terrace, and seven on the third and fourth terraces. Analyzing the limonite bands and soil changes in the cores, the investigators speculated that Monks Mound was built in a series of 14 stages. They further suggested that a population of ten thousand people could have provided the labor force necessary to build the mound. By dividing the number of stages into the time span indicated by radiocarbon datesÑA.D.900 to 1150 (250 years)It was calculated that the average life of each stage of construction was approximately 18 years (Reed et al. 1968:146).
Analysis of the cores suggests the following major stages:
Stage A: Primary flat-top mound,20 feet (6.1 meters) high, composed of black organic clay and rising from a natural sand floor. This black organic clay was similar to the gumbo mentioned in Moorehead's many descriptions and to the type of fill that was in another mound, Mound 72. This is the natural occurring substratum just below the A horizon in the area surrounding Monks Mound and may indicate that, indeed, the first mound built was of the soil closest to the surface.
Stage B: Flat-top mound rising 6 feet (1.85 meters) above Stage A.
Stage C: Roughly 10 feet (3.05 meters) above Stage A, extending from the north part of the fourth terrace to the south part of the third terrace.
Stage D: This stage was found only in the center and north cores about 8 feet (2.5 meters) above Stage C. It suggests that Stage D might be a terrace on the north half of Stage C.
Stage E: This extends from the south edge of the fourth terrace to the south edge of the third terrace.
Stage F: This is considered the "largest recognized construction stage, with a known thickness of seventeen feet, a north-south range of at least two hundred feet, and an east-west dimension of 175 feet" (Reed et al. 1968). At this stage, the mound is roughly 65 feet (19.8 meters) high. The typical black fill of Stage F is not found on the northern half of the mound, however, the sandy clay shows the same limonite bands found on the black fill and may be part of Stage F.
Stage G: Extends from the middle of the fourth terrace to the middle of the third terrace. Investigations suggest that it may be part of Stage F or a raised terrace on Stage F continuing the pattern indicated in Stages B and C.
Stage H through N: These stages average 4 feet (1.2 meters) in height. Their presence or absence in the various cores may suggest terracing (Reed et al. 1968: 142-144).
Thus, the 1960s work on Monks Mound seems to confirm the idea of artificial construction unless, of course, Stage A is considered an erosional remnant in place before the other work was done. It also seems to confirm earlier reporters' concepts that the mound was built up by successive additions.
That no tribe of Indians ever did, would, or could devote five years of constant labor to the erection of a single tumulus, would probably be admitted by everyone acquainted with Indian character.... It would seem, therefore, that the only reasonable supposition is that the mound was built by successive additions. How often these were made and how much was added at one period, must be wholly conjectural if we suppose the tribe living at this point to have been a populous one, which is probably the case Ñ say ten or twelve thousand Ñ it is not probable that they would have added more than the equivalent of the great terrace in any season. [Thomas 1907: 364]
Albeit for all of the wrong reasons, it seems that Thomas was probably right in both his conjectures about the stages of Monks Mound and the number of people living in Cahokia needed to support the construction of Monks Mound.
Other excavations on Monks Mound were conducted during the 1960s and 1970s. Those excavations contributed a great deal to our understanding of the complexity of this great earthwork. Among Me most extensive were the excavations on the fourth terrace conducted by Washington University and the Illinois Archaeological Survey. Much of the fourth terrace was completely excavated down to at least a meter in depth. The major find was evidence of a large structure at the north end of the terrace. The structure covered much of the north half of the terrace and was probably one of the largest structures at the Cahokia site. Its location on top of the big mound suggests it was certainly the most important building in town. No evidence was recovered as to its function, but it could have been a residence for the principal person of Cahokia or a public building.
The dating of the structure comes from several sources. First of all, it was not built during the last stage of construction of Monks Mound as there was approximately a meter of fill on top of it. The fill puzzled archaeologists at first since it contained no evidence of basket loading. The profiles through this fill present a typical soil profile, that is, a humic or A horizon and sterile-looking B and C horizons. The latter gave rise to the short-lived concept that a sterile zone had been placed on top of the remains of the last structure. However, it is probable that this last stage was built up the same as the other stages Ñ by basket loading. There may even have been a structure on top of it. If there was, it has probably been a few hundred years since the last structure and final stage were built. The process of soil formation has undoubtedly obliterated all traces of human activity.
This structure on the fourth terrace can also be dated by ceramic vessels found at the site. The vessels are polished black bowls with incised decoration, the famous Ramey Incised type, which is most diagnostic of the Stirling phase of the Cahokia sequence. A radiocarbon date for this structure was estimated at A.D.1150.
The University of Wisconsin-Milwaukee conducted excavations on the southwest corner of the first terrace, to determine the nature of a rise or small mound located in that area. Trenches through the area indicated that it was made up of a series of platform mounds. There had been buildings built on the surfaces of these mounds. Below the platform mounds was a series of extensive superimposed floors suggesting that this part of the first terrace had been built up by adding floors for intense activities. On these floors large structures were sometimes built around a courtyard or patio. All of these structures and patios showed evidence of intense activity, and most of the structures had been burned in situ. Extending northeastward from the southwest corner of the third terrace was a ridge of fill that appeared to have been covered since Late Mississippian times.
The UWM archaeologists also excavated the southwest corner of the first terrace for evidence of a post marking the north-south centerline of the Cahokia community. As predicted, at that point they uncovered a series of superimposed post pits on the slope of the platform mounds. These posts were not part of any structures, so their presence strengthens the hypothesis of a marked north-south centerline.
Radiocarbon determinations indicate that much of the first terrace mound building occurred during the twelfth century, or during the Stirling phase. Thus this activity must have been contemporary with the construction and utilization of the building excavated on the fourth terrace.
The University of Illinois at Champaign-Urbana conducted excavations on the first terrace as well. Excavations there focused on the central part of the first terrace and especially on the interface between the first and third terraces. That project indicated the great complexity of the construction of these terraces.
Washington University, in cooperation with the Illinois Archaeological Survey, dug some trenches in the ramp projecting from the first terrace. These excavations revealed that there had been steps up the slope of the ramp, indicating it was probably the major access to the first terrace.
The University of Wisconsin-Milwaukee excavated in the east lobes of Monks Mound in 1971 in cooperation with the Illinois Archaeological Survey. Financing was provided by the National Science Foundation and the Illinois Department of Conservation. Significant excavations were conducted under the lobes and adjacent to them. The excavations indicated that the surface under the lobes had been occupied in Sand Prairie times and determined that the slumping that produced the lobes took place some time in the past 400 years. They also recovered a striking engraved sandstone tablet. Furthermore, the excavations extended deep into the ground below the Sand Prairie surface giving a stratigraphic section beginning in Patrick phase times. All the currently defined phases of Cahokia were represented in this profile. Similar stratigraphic excavations were carried out by Washington University crews under the south ramp area.
Thus, the area of Monks Mound was apparently occupied by a group of farmers at least as early as A.D. 800. The first stage of Monks Mound was probably built in the Fairmount phase, or about A.D. 950. The Monks Mound area was probably the focal point of the Fairmount phase community, as it was in later times. During the late Fairmount phase and through the Stirling and Moorehead phases, Monks Mound was added to and enlarged several times, possibly as many as 18, until about A.D. 1200, when it achieved the form roughly as we see it today.
Whether Monks Mound was used during the Sand Prairie phase is not known, but there was evidence of Sand Prairie utilization of the area under the east lobes.
Evidence of the use of Monks Mound by historic Indians was found in the southwest and central sections of the first terrace during excavations by the University of Wisconsin-Milwaukee and the University of Illinois at Champaign-Urbana, respectively. Walthall and Benchley (1987) analyzed the material recovered and suggest that the first terrace had been the site of a French colonial mission and a settlement of the Cahokia Illini between about 1735 and 1752. The excavations produced historic Indian burials, house remains, and the remains of a small French chapel.
More recent historic utilization of Monks Mound began when Trappist Monks who owned the area built their monastery on a nearby mound and farmed the terraces of Monks Mound in the early 1800s. Amos Hill acquired the property in the 1830s. Hill built his house on top of Monks Mound; graded a road up the west side of the mound, dug a well on the second terrace, and leveled a small mound that had been on the southeast corner of the third terrace . More recent owners have built their houses and farm buildings below Monks Mound and have only occasionally attempted to farm the terraces.