I'm sitting here in the middle of the
marble of Verdi Peak which is a late
Cambrian to early Ordovician marble
sequence you can see it over in the Pequop
mountains a couple ranges over it
is an unmetamorphose
sedimentary sequence of sedimentary lime
stones but here on the back of Clover
Hill and the East Humboldt range and the
Ruby mountains has been intensely
metamorphosed and deformed and right
here in particular it's a kind of rock a
variety of deformed rock we call mylonite
and the key characteristics of
this that you can see it's a
well-developed foliation you can see the
rolling kind of a gently folded
foliation shears cutting through it and
when you look at those foliation
surfaces not the planar surfaces such as
right here you'll see a distinct
stretching and deforming of the calcite
grains and the marble in this case
they're tending over this way and and
that's the direction
they have all along the Ruby mountains
in these Humboldt ranges toward the west
northwest and that we interpret as the
direction of shearing in a very early
stage of these of the development of
these rocks so when that shearing
or ductile faulting smearing out if you
like was going on these rocks were
likely at depths of at least fifteen to
maybe even as much as 20 kilometers and
the study of those fine-grained micro
shear zones and deformational features
in this mylonite suggest that that
they the rocks were being pulled off
toward the west northwest and that
process of pulling them over lying rocks
ten or plus kilometers to 20 kilometers
of rock up off the top of these is what
ultimately exhumed or brought to the
surface at least brought closer to the
surface the Ruby Mountains in East
Humboldt range
