Cosgrove Ruin. Dendrochronology (tree ring dating) determined that the wood used in the dwellings were cut between 1276 and 1287. The region provided for growing, gathering and hunting food. To visit the namesake dwellings, visitors are required to hike a well-traveled trail loop with several foot bridges over a stream. The entire walk takes about an hour. The hike begins at an elevation of and ends at . Modern history Though local Native American Indians were aware of the location of ruins, the first European contact with the Gila Cliff Dwellings was by Henry B. Ailman (an emigrant to New Mexico who was residing in Silver City at the time). In the summer of 1878, Ailman and several friends were summoned to serve for jury duty, and in an effort to avoid the summons, they organized a prospecting trip to the Gila River, where they subsequently came upon the site. Throughout the following years, many visitors would study the dwellings. Soon the site became more accessible, and in the 1890s the Hill brothers had established a resort at the nearby Gila Hot Springs. The Hill brothers would begin the first tours to the ruins for their guests. In June 1906, Rep. John F. Lacey of Iowa and chairman of the House Public Lands Committee introduced a bill for the regulation of prehistoric sites. The Act for the Preservation of Antiquities, commonly known as the Antiquities Act, authorized the US President to set aside land that contained prehistoric and historic ruins by executive order. These federal reservations were called national monuments and were to be managed by the Interior, Agriculture, and War departments, depending on which agency had controlled a particular site before it was withdrawn for preservation. In December 1906, Gila Forest Supervisor R. C. McClure reported to the chief forester in Washington, D.C. that the Gila Cliff Dwellings warranted preservation by the national government to avoid further removal of artifacts by hunters and other prospectors. Several mummified bodies had been found at the Gila Cliff Dwellings location, though most were lost to looters and private collectors. In 1912, a burial ground was found; a mummified infant later referred to as "Zeke" was located. The discovery gained national attention and increased the monument's popularity and visitor numbers. In turn, additional improvements were made in the following years. The mummy is the only known mummy to be acquired by the Smithsonian