Tectonic processes (answer sheet)
1. Use the keywords from the box below to help you complete the following
summary.
Kaikoura Mountains (Seaward Kaikoura Range) has been folded as a result of tectonic
uplift along the boundary of the Australian and Pacific Plates. The mountains are
relatively young, actively uplifted mountains composed of greywacke that is often
jointed, shattered and easily eroded by mass-wasting, frost action, freeze-thaw, gravity,
and running water. (all influenced by climatic processes too).
The land of the peninsula was once the sea floor; that was many millions of years ago.
Uplifted high, the land continues to rise – the peninsula by about 3mm per year and the
Kaikoura Ranges by 10mm per year. The meeting of two of the Earth’s great crustal
plates causes the mountains of the land to build while ‘next door’, out at sea, it causes
the deep furrow of the Hikurangi Trough to form.
Kaikoura Peninsula was once an Island – hundreds and thousands of years ago. Over
time, river gravels eroded from the Kaikoura Ranges and filled the shallow sea that
washed between the island and the mainland.
Before the peninsula was an island, it was a sea floor. But so was much of New Zealand
then, millions of years ago.
Around 100 million years ago, under the enormous pressure of the sea, limestone and
siltstone started to be compacted into layers on the sea floor. Then, around 15 million
years ago, massive earth movements folded and twisted the layers, then started
shunting them skywards, up out of the sea.
Over the past 125,000 years, wave action has cut the land into platforms, during times of
relative stability, before uplift has occurred again. The top of today’s peninsula is the
oldest wave-cut platform. Here you will find beach gravels that are identical to the
shoreline. The peninsula’s newest platform is at sea level. The peninsula continues to
rise today. Plate boundaries and active faultlines make this area of New Zealand, both on
land and under the sea a geologically dynamic place. The peninsula is currently rising at
the rate of about 3mm every year.
sea, 3mm, greywacke, 100, Hikurangi, shallow, 125,000, tectonic, island, siltstone,
10mm, freeze-thaw, folded, limestone, build, 15, Seaward Kaikoura Range,