In 1876, an American by the name of Benjamin Smith Lyman submitted to the Japanese government a geological map of ‘Yesso’, which had been compiled under his direction. This map displayed the assumed stratigraphy of Hokkaido, in northern Japan, and is considered the first modern geological map to be produced by an Asian state. This provided a new means of comprehending territory, at exactly the moment the land in question was being re-presented as Hokkaido. The strata exhumed in the course of mapping this land at depth were not limited to those under the Earth. The map was assembled atop a history of Japanese control over the region, one which accounted for the precocious presence of an earlier American survey, conducted under the previous Tokugawa government, which had sought to map mineral deposits in this land of Yesso. These in turn reflected a longer history of mineral extraction, present in the earliest accounts of Ezo, and the motivation for Japan to have long ‘held the reins’ over this amorphous region. The 1876 geological map is a striking example of colonial modernity, through which we are able to observe the institutional mimicry characteristic to, and increasingly emphasized in the study of, late-nineteenth century inter-imperial society. The presence of this map challenges us to recover the various strata atop of which this imperial sociability was able to flourish, and examine the role of the map in incorporating a modernizing Japan within a globally-comprehensible means of territorial authority and control.