There were a number of "interface" cards created (Universal Connecting Bars on the German Carcassonne Forum), which had a section of water along one side and some game tile sections on the other. You could then place any game on one side, and a different one on the other, but they are always separated by the strip of water. It included strips for Amazonas, Ark of the Covenant, Carcassonne I, Gold Rush, H&G v1, Mayflower, Over Hill and Dale, South Seas. Of course, you could also use these as start blocks, similar to the way the one in Mayflower/New World is used.
Since the originals are not (currently) available to download, here are examples of each as a flavour of what I've been mentioning ...The Amazonas ones are based on 4x single tiles, while the double-tile blocks appear to be a mix of the same width as standard tiles, or half width.
Started by Lord_Wishmaster
Started by Scott
Started by asparagus
Started by SRBO
Started by Decar