  We have examined extended structures, bridges and arches, in computer
generated, non-sequentially stabilized, hard sphere deposits. The bridges and
arches have well defined distributions of sizes and shapes. The distribution
functions reflect the contraints associated with hard particle packing and the
details of the restructuring process. A subpopulation of string-like bridges
has been identified. Bridges are fundamental microstructural elements in real
granular systems and their sizes and shapes dominate considerations of
structural properties and flow instabilities such as jamming.
