INTRODUCTION AND ACKNOWLEDGMENTS The Bartlett Trough, which extends in a flat arc convex toward the north from the Gulf of Gonaive westward into the Gulf of Honduras, has a length of 1570 kilometers, a maximum width of 160 kilometers, and a depth of nearly 4000 fathoms, or about 9 kilometers below the highest points along the rim. Having contiguous land areas on both sides and at the ends, it possesses advantages for geologic research not afforded by other great submarine troughs. The north rim of the trough is exposed for the greatest distance where it coincides with the mountainous south coast of Cuba for 385 kilometers. The investigation here described has been devoted to the structural geology of this exposed portion of the Bartlett Trough and the areas immediately adjacent to it. During a geologic examination for the Cuban Government in December, 1930, the fresh excavations along the new Santiago . . .