The study of Devonian sediments is taken as a starting point in the analysis of late orogenic movements in the Caledonian-Appalachian mobile belt. It is assumed that this belt drifted ap art after the Devonian Period. The sedimentary sequences of 14 main Devonian outcrop areas, from Spitsberge n on the north to New York State on the south, provide evidence of times of deposition and erosion, in marine or nonmarine environments, and rates of sediment accumulation. The Old Red land mass grew southeastw ard in late Silurian and Early Devonian times in Scandin a via and Britain. Later in the Devonian , it grew westward in the Appalachians. These times of growth were coincident with the main Caledonian and Acadian phases of deeper crustal mobility. The geometry of movement of in dividual basins within the Old Red land mass is analyzed by use of paleocurrents, facies variation, provenance of sediments, and thickness variations. A distinction can be made between w ell-defined, relatively small, intermontane basins, and the commonly much larger, extramontane basins. The extramontane basins characterize both flanks of the landmass, whereas intermontane basins are typical of the central and northern parts. Basin mobility, as indicated by rapid down warp rates, characterized most of the land mass during Silurian and Early Devonian times. Great mobility was restricted to East Greenland , western Norway, and northeastern Scotland during the Middle Devonian , and to the Appalachians during the Late Devonian . Basin movement generally reactivated folding along trends already present in The Gander Conference, an International Conference on Stratigraphy and Structure Bearing on the Origin of the North Atlantic Ocean, was held in Gander, Newfoundland, August 1967. The conference gave geologists familiar with the areas bordering the North Atlantic Ocean with an opportunity to present their knowledge and ideas to colleagues dealing with similar rocks and structures. This publication contains most of the papers that were presented at that conference and a few others that were prepared for the sessions.