Triassic Park
Park at the suggested location, walk up the track until you get
near the published coordinates, and then you will be close to the
red dot on the following map:
Occasionally you will find what appear to be recent shells in
the hills, hundreds of meters above sea level, and you may have
asked yourself: "How on earth did these get up here?"
The answer is that New Zealand has been under sea level a number
of times. And as it has been pushed back up above sea level, the
sea floor ended up where you are seeing evidence of marine fossils
right now.
Before 650 million years ago, instead of all the continents we
have today, there was a huge land mass on Earth scientists have
called Gondwana.
About 650 to 380 million years ago the area that is now New
Zealand was nothing more than a large active volcanic ridge to the
East of Gondwana. Over the next 10 million years, the pressure of
the tectonic plate from the east pushed the New Zealand area and
caused it to collide with Gondwana, creating an uplift of the sea
bed. Further volcanic activity, and further pushes from the plate
from the east in a westerly direction caused further repetitions of
the sea floor to be pushed into Gondwana, in a number of "folds",
causing more of the the sea floor to rise above sea level. At this
stage the area that is now New Zealand was still part of
Gondwana.
Around 85 million years ago, a split appeared between Gondwana
and the New Zealand area, and for the next 15 million years these
two areas drifted apart. These two areas are now known as Australia
and New Zealand.
After this period of drift, by about 25 million years ago, New
Zealand had dropped mostly below sea level, where it remained for
about 5 million years until the currently active process started:
New Zealand was once again being pushed up by the tectonic plate
that lies to the the east.
This process has made New Zealand a geological area with an
amazingly diverse set of layers in a comparatively small space. The
top of the South Island is especially rich in geological
diversity.
Due to the processes explained above, New Zealand's oldest
rocks tend
to be towards the western edge of the country. Volcanic activity,
the process of being pushed into Gondwana, being under water, and
then being pushed up again has created layers of rock from the
Cambrian period (600 million years ago - Cobb
Reservoir). The most advanced forms of life during the Cambrian
period were animals with hard shells (such as
Trilobytes)
The area you will visit for this earthcache was under the sea
approximately 195-130 million years ago. This was the period when
the very first
dinosaurs and very primitive mammals first appeared.
You are unlikely to find any remains of dinosaurs and mammals at
GZ, as this is an area that used to be the seabed. But it does have
an abundance of evidence for lots of shells. Have a walk along the
track and investigate the rocks. Once you are looking, you'll be
surprised how many fossils are right there.
LOGGING REQUIREMENTS
You may log your visit without prior approval as long as you
send the required answers to the cache owner by email at the same
time. Please note that you will be required to do a little research
to get some of the information.
- The fossils at GZ are part of a sedimentary rock. The primary
component of this sediment is neither sand nor mud. Email the cache
owner what kind of sediment formed the majority of these fossilised
rocks. DO NOT POST THIS INFORMATION IN YOUR LOG.
- What is the popular name given to the band of ultramafic rock
in the top image, and describe how ultramafic rock comes into
existence. Is this band, of which Dun Mountain is an obvious
feature, Intrusive, Volcanic, Metamorphic or Ultrapotassic? DO NOT
POST THIS INFORMATION IN YOUR LOG.
- Locate a fossil. Take a photo of your GPS with the current
position readable next to a rock fossil - TO BE POSTED WITH YOUR
LOG.
CAUTION: Maps will show "Hart Rd" going right to the cache site.
This is a paper road - the walking track starts at the provided
coordinates.