The topography of the Great Meadow rises in gently undulating steps from
the base of campus to the elevation of the top of the bike path and the
East Fields. The gently undulating steps or benches are marine terraces,
each of which represents old ocean floor that has been uplifted to its
present position. Marine terraces are common all along coastal
California. In Santa Cruz, there are at least five terraces, the first
of which is called the Mission Street or Highway 1 terrace.
The corner of Laural and California Streets lies at the seaward edge of the
Highway 1 terrace. The second terrace is the Western Drive terrace, and
the third terrace is represented on campus by the flat area near the
Carriage House, the Campus Facilities Office, the faculty apartments, and
the campus garage, and is just visible in the photograph to the left.
Terraces higher then the third are older and less well preserved on
campus. One reason the upper terraces are not well preserved on campus is
the role of the underlying marble in the development of karst topography.
Karst processes, such as sinkhole formation, cause the ground surface to
undulate, and lose the flat, bench-like quality of the marine terraces.
The photograh to the left shows these undulating surfaces that may once
have been marine terraces and started their life at the beach.
But not all of the bedrock in this area is marble. The outccrop on the
right, located near the top of the bike path, is quartzite; a metamorphic
rock composed almost entirely of fused quartz grains. Since Quartzite is
composed nearly entirely of quartz, its protolith must have also been
extremely rich in SiO2. About the only rock that fits this description is
an extremely mature auartz-rich sandstone, like those formed in beach
environment. Ocean waves and currents produce beach sands that are rich in
the resistant minerals quartz and feldspar. If this type of sand turned
into a rock, and then brought to metamorphic temperatures and pressures,
quartzite forms. From geological mapping efforts, the
campus quartzite appears to be surrounded by marble. Apparently, the
quartzite
occurs as isolated lenses or chunks within the campus marble and/or
schist. Quartzite is extremely resistant and forms many of the knobs or
small hills in the Great Meadow area. At other quartzite localities,
this unusually resistent rock often forms steep
cliffs, like these in Alabama.
The photograph at right is a typical quartzite outcrop. Note its massive
apperance and lack of preferred orientation. It is light colored on most
surfaces, and reddish only in cracks and fractures through which water has
percolated. On fresh surfaces, the quartzite has a sugary texture
comprised of white, transluscent quartz grains. Impurities include
graphite, mica, and feldspar.
A closer view of the rock reveals
individual quartz grains that will easily scratch glass or steel blades.
