Sea level change and field work techniques

We are considering some of the evidence for sea level changes and show some of the field work techniques used by staff and students from Pirinoa Primary School.

See you in the field!

Evidence for Sea Level Change Locked In The Rocks

In our PLD trip with Kahutara School, we considered the boundary between greywacke and sandstone. We believe that greywacke formed in deep seas as a result of sediment avalances off the continental shelf onto the abysal plain. The sandstone formed in shallow seas.

Unconformity

So the unconformity marks a point of sea level change from deep water to shallow – in fact there were almost certainly many many sea level changes during this time because the unconformity represents a period of time of over 100 million years.

Sandstone layer containing lots of fossils

In the photo (right) the greywacke is folded as a result of the slumping of sediments during avalance events – providing evidence that the sedimentary rocks originated from deep sea environments.

The photo (left) shows a sandstone layer containing lots of fossils – these creatures lived in shallow water sea environments approximately 10 million years ago. They provide evidence that sea level changed.

Sea level changes and field work techniques

More recent events

In our previous posts also looked at some of the ancient events that occurred on Earth and considered the evidence that is locked in the rocks of the South Wairarapa.

In this post, we are considering some of the evidence for sea level changes and show some of the field work techniques used by staff and students from Pirinoa Primary School.

84,000 years ago, the sea level was much higher and cut out a wave cut platform/Interglacial Terrace – blue line in photo below.

This was followed by an earthquake (Earthquake 1) and this lifted the sea floor above sea level and a new platform was cut. This process of earthquake and uplift has been repeated with at least 3 more earthquakes and each time a new platform was cut.

Field work techniques

ABOVE: A Pirinoa Primary School student hammers the greywacke (right) which makes a solid, almost ringing tone. Hammering the sandstone (left) makes more of a ‘thud’ sound.

Meanwhile other students closed their eyes (below) and identified the rock type based on the sound produced.

Measuring slope (dip) and direction (bearing)

Pirinoa students lie on a bedding plane whilst measuring the slope (dip) of the bed and its bearing.

Testing the hardness of the rock – often it is a valuable aid to identifing rock types between localities.

Geological map showing dip and strike of the sandstone

what we've been up to

Outdoor Science Adventures

Check out some of our outdoor science adventures. Field Based STEM facilitators are all passionate and experienced field workers.
Some have spent their working lives in Crown Entities such as GNS, others are experienced teachers with huge experiences leading EOTC, and some have combined their working lives in education and the scientific community. At Field Based STEM, we are proud to claim that every one of our facilitators can provide unrivaled field based experiences.

Sea level change and field work techniques

We are considering some of the evidence for sea level changes and show some of the field work techniques used by staff and students from Pirinoa Primary School.

St. Theresa’s Primary School – Matakitaki a Kupe Reserve

This is a story about pillows but not your usual feathery ones, these pillows are made of basalt, deep underwater. The Matakitaki-a-Kupe has these basalt pillow lava formations in questions and we are taking a trek with teachers from St/ Theresa’s Primary School to look at them.