Geology Reference
In-Depth Information
documents (reports, drawings and calculations), thus taking legal
responsibility. Details for career routes for various countries are set
out in Appendix A, together with links to a number of learned societies
and details of professional institutions that an engineering geologist
might aspire to join.
'out of the oven' - not
seen at Earth's surface
2.7
Typical dry
density
Mg/m
3
yp
y
density
Mg/m
3
Fresh
Slightly weathered grainte as recovered from a borehole and
in thin section under microscope
Slightly weathered grainte as recovered from a borehole and
in thin section under microscope
UCS up to about 250
MPa
Looks fresh in hand
sample but joints may be
stained
Slightly
Weathered
Weathering
and leaching
h
ring
an
n
nd
l
e
aching
Several hammer blows to
break sample
Discoloured, weakened
and jointed but still
'rock'
We
e
th
Moderately
Weathered
Fines
washed
out of
relic
fabric
nes
ashed
it of
lic
bric
Needs hammer to break
Becoming soil like but
doesn't disintegrate if
placed in water
Highly
Weathered
Clay
remains in
place
Clay
remains in
place
Many micro-cracks
Broken by hand
Feldspars soft
-
grooved
with pin and sample
disintegrates in water
Completely
Weathered
1.2
2
1.7
1.7
Micro-cracks may be
sealed with clay
Original texture lost
Open
porous
texture
pe
n
rou
us
xtur
e
completely weathered granite with texture retained (feldspars
decomposed to white kaolin). After adding water it completel
disaggregates (slakes)
completely weathered granite with texture retained (feldspars
decomposed to white kaolin). After adding water it completely
disaggregates (slakes)
Residual
Soil
Much of quartz has been
dissolved.
Collapse and
reworking
ollapse an
d
ki
Typically red, clay rich
2.0
20
