Molecular self-assembly due to chemical interactions is the basis of bottom-up nanofabrication, whereas weaker intermolecular forces dominate on the scale of macromolecules. Recent advances in synthesis and characterization have brought increasing attention to two- and mixed-dimensional heterostructures and it has been recognized that van der Waals (vdW) forces within the structure may have a significant impact on their morphology. Here, we suspend single-walled carbon nanotubes (SWCNTs) on graphene to create a model system for the study of a 1D-2D molecular interface through atomic resolution scanning transmission electron microscopy observations. When brought in contact, we observe radial deformation of SWCNTs and the emergence of long-range linear grooves in graphene revealed by three-dimensional reconstruction of the heterostructure. These topographic features are strain-correlated but show no sensitivity to carbon nanotube helicity, electronic structure, or stacking order. Finally, despite random deposition of the nanotubes, we show that the competition between strain and vdW forces results in aligned carbon-carbon interfaces spanning hundreds of nanometers.