Velocity-depth models, created by performing one-dimensional ray tracing on large offset variable-angle sonobuoy data, and single channel seismic reflection data were used to differentiate acoustically smooth and rough basement in the Venezuelan Basin. Both the smooth and rough crust are thicker than "normal" oceanic crust. with the smooth crust being the thicker of the two. The velocities of the layers within the smooth and rough basements are identical. The only differences in velocity structure of the definitively igneous layers are that all of the smooth crust layers are thicker than the rough ones. This difference in thickness can be attributed to the possible extension of the rough crust as well as the Caribbean Cretaceous basalt province, a large igneous province, ovelying the smooth crust. Based on cores of the Caribbean basalt province from DSDP Leg 15, the basalt province is a series sills and flows which causes the crust to be acoustically smooth. The province is characterized by thin layers that have a velocity between sedimentary and typical igneous velocities. These transitional thin layers which appear to have sub-layers, have the same acoustic characteristics as the layers directly below them that have typical igneous velocities. The transitional layers are possibly a mixture of basalt province's flows and sills with pre-existing seafloor sediments. The chronological relationship between the extension of the rough crust and the emplacement of the basalt province on the smooth crust was not determined. Observations from the single channel data suggest that the extension occurred first in some areas, but happened second in others. Processing of the multi-channel seismic reflection data would improve the resolution of the reflection data and thus increase the possible observations.