A Better Idea of Formation and Karst Landscapes

Welcome back to my blog! 

Today I will be discussing the Waitomo Caves in New Zealand again in a more in-depth explanation of their formation as it relates to my new understanding of Karst Landscapes.

So, you may be asking "What is Karst?"

Karst is a term that derives from the Jugoslav "kars" which means stone. This term Karst refers to the solution features of a certain type of stone called limestone which occurs on a plateau. Limestone is classified as any rock that has 50 percent or more calcium carbonate contained inside. In fact, the surface of the Earth has 10 to 20 percent limestone.  

Source: Groundwater Systems
This picture is a zoomed-in map showing major karst regions in purple. The land masses circled in red are the North and South islands of New Zealand. The karst region shown on the North island is the area of Waitomo. 

   Caves as Part of Karst Landscapes

The idea here is that limestone and dolomite are both susceptible to karst development. This can lead to the formation of valleys, sinkholes (dolines), and caves. These formations can occur because of a weathering process called dissolution, where material erodes.

So how did the Waitomo caves form anyway?

Well, there is a debate over how caves form! The two methods suggested are a Deep Phreatic reaction and a Shallow Phreatic reaction. Let me explain below and then I will tell you which I think made the Waitomo Caves. 

Deep Phreatic Reaction

In a Deep Phreatic Reaction, the formation occurs below the water table. A blind river goes into the soluble limestone underneath and fills or carves in empty spaces via dissolution. The water source then gets closed off and the caverns are left, along with whatever water has pooled in them.

Source: Under Florida
This image is a visual diagram of the Deep Phreatic Reaction methof of cave formation. The blind river flows into a fissure in the limestone creating a cave and leaving water to pool.

Shallow Phreatic Reaction

In a Shallow Phreatic Reaction, cave formation happens while the limestone is absorbing water and becoming saturated and weak. This area is exposed when the water table drops. The new cave is made at the water table's former level. This activity of the water table dropping exposes the cave to a zone of aeration, while the water carries away the eroded limestone.

Source: Geschichteinchronologie
This image shows the Shallow Phreatic Reaction formation method. The water table was once at the former level and is now at the current water table level. When the level was high, the vulnerable limestone in the area became saturated and weak. Then, when the level dropped to its current state, the saturated stone eroded and was carried with the water table, leaving a cave in its place. 

My Hypothesis

Based on what I learned, my hypothesis is that the Waitomo caves were formed because of a Deep Phreatic Reaction because the entrance to the cave is an opening in the top of the cave which can allow a flow of water to form the cave. There is also a large amount of water pooling at the bottom.

Source: Stay Base
This picture shows the pooling of water in the bottom of the cave and a group of people attached to a tether that helped them descend into the cave's entrance.

That's it for now! Tune in next time!

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Resources:

Image Resources

After, M. (1997). Cave Forming By Groundwater [Digital image]. Retrieved April 2, 2017, from http://www.geschichteinchronologie.com/welt/wasser-u-grundwasser01-d/021-cave-forming-by-groundwater-ENGL.png

Groundwater Systems [Digital image]. (n.d.). Retrieved April 2, 2017, from http://images.slideplayer.com/39/10887337/slides/slide_27.jpg

North, L. (2016, October 19). Karst Diagram [Digital image]. Retrieved April 2, 2017, from http://underflorida.com/images/karstdiagram.png

Waitomo Tubing Cave [Digital image]. (n.d.). Retrieved April 4, 2017, from http://cdn.stayatbase.com/image/resize.php?url=images/blog/new-zealand/waitomo_tubing_cave.jpg&width=1600

Article Resources

New Zealand Ministry for Culture and Heritage Te Manatu Taonga. (2015, October 19). Limestone country – Te Ara Encyclopedia of New Zealand. Retrieved April 03, 2017, from http://www.teara.govt.nz/en/limestone-country

Under Bowling Green. (2016, October 19). Retrieved April 03, 2017, from http://underflorida.com/learn.html

Location and Formation

Location

The beautiful Waitomo Glowworm caves are relatively located on the North Island of New Zealand, in the region referred to as northern King Country. Their actual coordinates are 38°15.58′S latitude and 175°06.84′E longitude. 

Source: Google Maps
This map shows the area of Waitomo where the caves are located. The area is outlined and tinted in red.

The Waitomo area is small, in relation to the rest of the island, but the area is a popular ground for tourists and adventure-seekers.

Source: CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=603482
This photo shows the overhead entrance into the caves surrounded by beautiful plants.

Above you see the entrance to the cave which is a significant obstacle to tourism because its location hinders accessibility. The entrance is located on top of a series of hills. This means, to enter the cave, tour groups descend either by rope or by ladder into the narrow cavity, which may not appeal to those with physical disabilities or claustrophobia. The caves are also too narrow to fit a large boat for tours so the tour agencies make do with the use of either personal rafts or small boats that can only accommodate a handful of people. As a result, the tours fill up quickly. Additionally, there is no possibility of night tours because of safety precautions, so all the groups must pass through the cave in the day time only.

Formation

The caves were formed on an earthquake fault. A fault, according to the USGS Earthquake Hazards Program's Earthquake Glossary, is "a fracture along which the blocks of crust on either side have moved relative to one another parallel to the fracture". This makes it possible for the rain that is responsible for creating the limestone crystals to enter the cave from above. 

Source: Western States Seismic Policy Council
This graphic shows an earthquake fault to explain the formation of the caves. An earthquake occurs along a fault in the Earth. The place where this quake occurs is called the focus. The relative location to the focus on the Earth's surface is its epicenter. This earthquake causes the weak fault to rupture further, creating a cavity.  

Limestone crystals are part of the Earth's process of decreasing carbon dioxide to regulate its average temperature. In this process, some of the carbon dioxide on Earth solidifies, in the form of limestone and dolomite, and stays there until the Earth needs to use it again.

Extra Cool Video

This video on YouTube by National Geographic lets you take a 360 degree look at the inside of the Waitomo Caves. Enjoy! 

Source: YouTube

 References Visual Media

B. (2016, October 18). Retrieved February 20, 2017, from https://www.youtube.com/watch?v=QjqGlLVIAtg

Handbook [Photograph found in Earthquake Size and Severity, Western States Seismic Policy Council]. (2008, February 24). Retrieved February 20, 2017, from http://www.wsspc.org/wp-content/uploads/2017/01/Handbook_FINAL_New.pdf

Map of Waitomo Area [Map]. (n.d.). In Google Maps. Retrieved February 20, 2017, from https://www.google.com/maps/place/Waitomo, New Zealand/@-38.2393291,174.927485,11z/data=!4m5!3m4!1s0x6d6cb7b215429a03:0x500ef6143a316b0!8m2!3d-38.2615305!4d175.1145451!5m1!1e4

Shook, J. (2014, December 30). Waitomo Cave Entrance. Retrieved February 20, 2017, from https://commons.wikimedia.org/w/index.php?curid=603482 (Originally photographed 2005, October 19)

References Articles

Earthquake Glossary - fault. (n.d.). Retrieved February 20, 2017, from https://earthquake.usgs.gov/learn/glossary/?term=fault

Waitomo Caves. (2017, February 17). Retrieved February 20, 2017, from https://en.wikipedia.org/wiki/Waitomo_Caves

Waitomo Caves, Waikato. (n.d.). Retrieved February 20, 2017, from http://www.topomap.co.nz/NZTopoMap/nz56788/Waitomo-Caves/

Waitomo Glowworm Caves. (n.d.). Retrieved February 20, 2017, from http://www.waitomo.com/Waitomo-Glowworm-Caves/Pages/default.aspx

Monday January 23, 2017

Welcome to my blog!

My name is Madisyn Yaron and I live in Aurora Colorado, which is quite a distance from CU Denver. Online school is wonderful because I don't have to burn two hours commuting. I am a pre-3D Animation major (formerly Computer Science major) in my third year at the university but am technically in the first year of my major. In my free time, I enjoy browsing YouTube for funny videos, singing to music, and talking with friends.

This semester, I have chosen to explore The Waitomo Glowworm Caves on the North Island of New Zealand.

Source: Shaun Jeffers Photography

I chose this location because New Zealand is home to beautiful places, many of which are featured in popular movies. I really want to visit someday and experience the beautiful country with my own eyes and am excited to learn more about it!