It was self-evident that if that process went on long enough, the arc of habitats reaching west from, say, Greenwich would make contact with that growing east from Rio. The increasingly narrow bands of unused material and recyclable junk between segments became the boneyards, and might have disappeared altogether had they not been so useful—in the early going, as materials depots, later as political buffers and as liminal zones, akin to frontiers, to which people could escape when they had learned that the close-packed life of space habitats was not for them. The one halfway between Greenwich and Rio was called Cape Verde. Other boneyards, proceeding westward from Cape Verde, were Titicaca, Grand Canyon, Hawaii, Kamchatka, Guangzhou, and Indus. Completing the circle, the one between Baghdad and Greenwich was called Balkans. Some were bigger than others. Guangzhou, which formerly had separated the Aïdan and Camite segments, had been used up entirely as the populations to either side had grown.