  We present a systematic study of the topology of the vortex solid phase in
superconducting Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ samples with low doses of
columnar defects. A new state of vortex matter imposed by the presence of
geometrical contours associated with the random distribution of columns is
found. The results show that the first order liquid-solid transition in this
vortex matter does not require a structural symmetry change.
