Is this a marker left by the French explorer Robert Cavelier de La Salle two years before the Jacques Marquette and Louis Joliet expedition in 1673? If so, then European explorers were traveling in Illinois earlier than is commonly accepted. The Program on Ancient Technologies and Archaeological Materials was asked to examine the Ellington Stone (ES) and to determine, if possible, the type of rock and the date of the carvings.

Geological examination: Three geologists from the Illinois State Geological Survey (ISGS), Randy Hughes, Zak Lasemi, and Rod Norby, examined the ES with hand magnifiers and a low-powered (5X to 80X) binocular microscope, comparing the rock to ISGS samples of limestone and dolomite from different parts of the Midwest. Based upon the color, texture, and types of bryozoan and brachiopod fossils, they agreed that the ES is less like the white, coarse-grained limestone of the Burlington Limestone Formation and more like overlying Warsaw and Keokuk layers typical of Adams county, western Illinois.Thus, the type of rock is perfectly consistent with an origin near Quincy, Illinois.

Dating: Dating the carvings is much more difficult because the ES was removed from its original findspot almost a hundred years ago and it was cleaned at least once: Mr. Cook's carpenters scraped dirt and debris out of the letters and numerals with spikes and screwdrivers. In theory, one could estimate the age of the carving based upon a) its stylistic features, b) the physical weathering of the carved areas vs. the rest of the surface, or c) by obtaining a radiocarbon date from organic material embedded in the carvings.
We have no comparable stone marker to examine for stylistic similarities. There is slight variation in surface textures, but not enough to help estimate the date of the carvings. The overall preservation is quite good, suggesting that the ES was protected from the weather after it was pulled out of the creek bed. The third option, obtaining a radiocarbon date, was ruled out after a microscopic exam by another ISGS geologist, Brandon Curry, revealed only a few hyphae, or mold filaments inside the numeral seven.

If the Ellington Stone were discovered today, we would recommend that it be left in situ until archaeologists and geologists could study and take samples from the surrounding soil matrix, plant materials, and adjacent rock formations. Analyses of these contextual materials might then help us determine when the numerals and symbols on the ES were carved and when the stone came to rest in this location.