  This study presents a tomographic survey of a subset of the outer halo (10-40
kpc) drawn from the Sloan Digital Sky Survey Data Release 6. Halo substructure
on spatial scales of $>3$ degrees is revealed as an excess in the local density
of sub-giant stars. With an appropriate assumption of a model stellar isochrone
it is possible for us to then derive distances to the sub-giant population. We
describe three new candidate halo substructures; the 160- and 180-degree
over-densities (at distances of 17 and 19 kpc respectively and radii of 1.3 and
1.5 kpc respectively) and an extended feature at 28 kpc that covers at least
162 square degrees, the Virgo Equatorial Stream. In addition, we recover the
Sagittarius dwarf galaxy (Sgr) leading arm material and the Virgo Over-density.
  The derived distances, together with the number of sub-giant stars associated
with each substructure, enables us to derive the integrated luminosity for the
features. The tenuous, low surface brightness of the features strongly suggests
an origin from the tidal disruption of an accreted galaxy or galaxies. Given
the dominance of the tidal debris of Sgr in this region of the sky we
investigate if our observations can be accommodated by tidal disruption models
for Sgr. The clear discordance between observations and model predictions for
known Sgr features means it is difficult to tell unambiguously if the new
substructures are related to Sgr or not. Radial velocities in the stellar
over-densities will be critical in establishing their origins.
