Geology of Canterbury - The Geological History of Canterbury NZ

Geology of Canterbury NZ

1. The Geology of Canterbury What is Canterbury Made Of?

2. Zealandia and the Deep History of Aotearoa Zealandia is the submerged continent that forms New Zealand, as well as New Caledonia, Norfolk Island and various other small islands. Zealandia originally separated from Gondwana ~83-79 million years ago. Approximately 23 million years ago it may have been completely submerged before volcanic and tectonic activity pushed the crust above sea level. Eventually forming the land mass of Aotearoa New Zealand that we recognise today. Today most of the landmass of Zealandia (94%) remains submerged beneath the Pacific Ocean. Aotearoa New Zealand is the largest part of Zealandia that is above sea level followed by New Caledonia.

3. Zealandia and the Deep History of Aotearoa https://youtu.be/E6Nyr78Mqyg?si=Q6o06EqJtOE4eDUj As you watch the animation, complete the captions in your workbook.

4. Greywacke Rocks! What is Greywacke? Greywacke or graywacke is a variety of sandstone generally characterized by its hardness, dark color , and poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size lithic fragments set in a compact, clay-fine matrix. It is a texturally immature sedimentary rock generally found in Paleozoic strata. Greywacke is the main building block of the Southern Alps.

5. Greywacke Rocks! https://www.youtube.com/watch?v=z13tAcSYVdo As you watch the video answer the questions on your question sheet.

6. Greywacke Rocks! What is Stratigraphy? Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy helps us to determine how old the rocks laid down during New Zealand’s Geological History are. The deeper down underground they are, generally the older the rock layer is. New Zealand’s Greywacke layer was formed sometime between 230-290 million years ago! Greywacke is some of NZ’s oldest rock and can be found in the Waipapa , Torlese , and Caples Terraines Greywacke of the Torlesse Terraine , Aoraki Mt. Cook

7. Greywacke Rocks! Using the New Zealand Geology Map you will map New Zealand’s basic geological regions on the blank map in your booklet by shading the relevant areas. Make sure to include a key. https://upload.wikimedia.org/wikipedia/commons/9/9d/New_Zealand_geology_map_with_key.png

8. What is Loess? In some parts of the world, windblown dust and silt blanket the land. This layer of fine, mineral-rich material is called loess. Loess is mostly created by wind, but can also be formed by glaciers. When glaciers grind rocks to a fine powder, loess can form. Streams carry the powder to the end of the glacier. This sediment becomes loess. Much of the South Island is covered in a layer of loess varying between 30cm and 20+m deep.

9. Loess in Canterbury The Port Hills are made of volcanic rock from the eruptions that formed Banks Peninsula. The volcanic rock is covered first by layers of volcanic colluvium soil, this volcanic soils itself coated by a layer of loess. This loess layer is typically 2 metres thick but in some places is as much as 20 metres deep.

10. Example of loess deposits on a section of the Port Hills near Wakefield Avenue, Sumner

11. Port Hills looking South-East from above the Avon-Heathcote Estuary A model of the Banks Peninsula the Port Hills are the volcanic ridge on the left

12. Braided Rivers https://braidedrivers.org/rivers/ A braided river is a type of river characterized by a network of multiple interweaving channels that separate and rejoin around small, temporary gravel or sediment islands. These rivers form in areas with a combination of steep gradients, high sediment load, and variable water flow. During periods of low flow, the river's current is not strong enough to carry all the sediment, causing it to be deposited and creating these gravel islands. As the water level changes, especially after heavy rainfall or snowmelt, the channels shift, and the river may temporarily join into a single channel before splitting again. This constant movement creates a dynamic, ever-changing river landscape. Braided rivers are relatively rare globally but are a common feature in New Zealand, especially in the Canterbury region, where they have played a significant role in shaping the Canterbury Plains.

13. Braided Rivers https://braidedrivers.org/rivers/ Click on the link to access the website on Braided Rivers. Read the information and use it to answer the 20 questions on the worksheet. Research how a braided river is created then draw a series of diagrams illustrating the construction of a braided river on the worksheet provided.