began an era of more responsible ownership, and encouraged archaeological investigation. Many artifacts were found at or near the surface. Ramey had a tunnel made nearly into the north face of the mound, but it revealed nothing of historic interest. By this time, people were beginning to consider the mound more within its context. A survey made for local dentist Dr. John R. Patrick in the 1880s marked the beginning of modern understanding of the Cahokia site as a whole, and its relationship to other sites in the area. Many archaeological investigations of the mound have taken place since then. One of the biggest began in the 1960s, when Nelson Reed, a local businessman and historian of native cultures, obtained permission to conduct excavations. He was trying to locate the high-status building (temple or palace) presumed to have stood at the peak of Monks Mound. By drilling cores at various points on the mound, his team revealed the various stages of its construction from the 10th to 12th centuries CE. Remains of a fairly recent house (presumably Hill's) were found, but no temple. In 1970 Reed returned to work at the mound, and adopted a new strategy: scraping away the topsoil from several patches with a backhoe, to a depth of around . This quickly revealed various features, including what appeared to be the outline of the temple. Further backhoe work in 1971 confirmed the shape of the presumed temple at over long, the largest building found at Cahokia. This technique was opposed by professional archaeologists because it destroyed several hundred years of stratification over most of the mound's summit, which was the evidence by which they could place and evaluate artifacts and construction. Reed's backhoe excavations revealed other significant features, such as a hole which seemed to have been the socket for a post about three feet (one metre) in diameter. The dramatic finds encouraged the Governor of Illinois to budget for an expansion of the Cahokia Mounds State Park. Preservation From the time the original urban society collapsed, the great mound became overgrown with trees, the roots of which helped stabilize its steep slopes. In the 20th century, researchers removed the trees in the course of work at the mound and park preparation. Reduction of groundwater levels in the Mississippi floodplain during the 1950s caused the mound to dry out, damaging the clay layers within. When heavy rainfall