GEOL 310 - Module 1

Introduction & Overview

Karst Systems & Processes The goal of Module 1 is to introduce you to some fundamental information you need to know about karst.

1. The first part of the module will look at karst basics:

o What is karst?

o What are caves?

o Definitions

o Concept of karst systems

2. The second part of the module will look at the processes and conditions that enable karst development

3. The third part of the module will cover where karst occurs around the world and in Canada

Three Dimensional Karst Landscape

Credit: Paul Griffiths

Learning Outcomes for Module 1

Upon successful completion of this module, you should be able to:

Describe the difference between a cave and a karst landscape

Discuss the importance of karst systems and its sub-components

Identify where karst occurs within Canada and around the world

List the fundamental conditions and requirements for karst development



Concept

Karst Systems & Processes One of the key concepts in understanding karst is to realize that we are dealing with a three dimensional landscape.

This landscape is not only dramatically exposed on the surface of the earth's crust, but also extends for some distance into the subsurface.

In 2004 cavers surpassed the 2-km mark in one of the deepest caves in the world that is located on the edge of the Black Sea near Georgia and Russia.

Requirements For Successful Completion Of Module

Karst Systems & ProcessesTo complete Module 1, you will need to:

1. Read through the following screens and complete the three learning activities as you go.

2. Next, complete the required readings as indicated and do the self-test quiz.

3. Finally, go over the discussion at the end of the module and submit responses to the Case Example M1: Lake Development (Graded)

Consider the following questions as you go through the module and readings:

1. Why is it important to learn about karst as a system, and how do caves fit into this system? 2. In what setting might you find lava tubes, and should they be evaluated using a system's approach?3. Are karst landscapes common phenomena worldwide, and in what parts of the world might some of the





greatest human usage of and/or conflicts with this resource occur? 4. Why and in what ways are caves and karst landscapes important resources? 5. Is there a difference between the terms 'karst system' and 'karst ecosystem'?

By understanding all parts of Module 1 you should then be comfortable to continue on with the other modules!

You should plan to spend between 5 to 6 hours to complete Module 1, including the readings and discussion questions’.

Review the checklist below to ensure you complete all items in this Module:

1. Read module contents2. Complete all learning activities3. Do assigned readings4. Review additional resources 5. Do self-test quiz6. Review the Summary and Wrap Up

7. Respond to discussion question

Karst Basics

What Is Karst?

Karst is a landscape or terrain that results from the weathering of bedrock types that are soluble in water.

These bedrock types are primarily limestone and marble, but can also include:

DolomiteGypsumHalite And in rarer cases sandstone and quartzite

A karst landscape is characterized by surface features such as sinkholes, a lack of surface streams and a subsurface network of openings.

Some of these subsurface cavities can be entered by humans, and are considered as caves - one of the best known features of a karst landscape.

Karst Basics

Alpine Karst Landscape from Vancouver Island


What Is A Cave?

There are many different definitions for a cave depending on circumstances and geographical location. The simplest and most commonly accepted is:

A cave is a natural cavity within the earth's crust that is connected to the surface. In addtions it has an opening that is penetrable by a human, and includes a zone of permanent darkness.

Other definitions can be found, some of which are very specific (e.g., about the size of the cavities). However, the above definition covers the three important aspects of a cave, its:

1. Formation

2. Size

3. Appearance

Caves typically form only a small portion of the cavities within a karst landscape (e.g., less than 0.01%) and as such should not be treated in isolation from other parts of the landscape.

In many cases a cave can be linked by smaller conduits and cavities to the surface.

Limestone Karst Cave


Karst Basics

What Is Pseudokarst?

Pseudokarst is a landscape that looks like karst, but was not formed by the dissolution of the bedrock. These landscapes can be formed by a variety of other processes such as:

Piping (the erosion of soil by percolating water)Permafrost melting (creates differential settlement of the ground)Volcanic eruptions (e.g., low viscosity lava flows forming lava tubes)Tectonic movement

Uplift (e.g., fissure-related openings and caves)

Karst Basics

What Is Paleokarst?

Paleokarst is ancient karst that has been infilled and buried by later geological processes.

Paleokarst itself can also, in certain conditions, undergo further karst development (or karstification).

Karst Basics

Window into Ape Cave Lava Tube, Mount St. Helen's

Credit: Tim Stokes

Paleokarst from South Africa

Credit: D. L. Reid

Where Does The Name "Karst" Come From?

The word karst comes from a German word Kras – which is a limestone plateau in the Dinaric Alps of Croatia and northeastern Italy.

This is the type locality for karst landscapes and was recorded as such on a topographic map for the area back in the 1700's.

Karst Basics

Why Is Karst Important & A Valuable Resource?

Karst is important for a wide variety of reasons.

On a global scale a significant portion of the earth's crust is underlain by limestone (and other soluble bedrock types) that have the potential to form karst.

An understanding of karst processes is therefore important, particularly where humans interact with this landscape.

Clean White Limestone with Dissolution along Fractures


Worldwide Distribution of Carbonate Rocks


Karst Basics

Why Is Karst Important & A Valuable Resource? continued...

Karst landscapes have certain features and resource values that are not present in non-karst landscapes.

Karst aquifers provide the main source of water in many parts of the world (25% of US groundwater come from karst).

Karst caves are sites for unique subterranean habitats, many of which have yet to be explored and studied.

Caves are also depositories (or storage sites) for critical information on past life forms (fossils), ancient cultures and paleo-climates.

Karst Basics

Why Is Karst Important & A Valuable Resource? continued...Most of our larger urban centres in British Columbia are situated away from areas underlain by karst. However, in other parts of the world (e.g., China, Southeast US) living on top of the karst landscape can present some special issues such as:

Ground subsidenceContamination of groundwater, and Damage to cave habitats

On Vancouver Island one of the principal concerns is the impact of forest development activities on karst including:

The intersection of shallow cavesThe redirection of water flow during forest road constructionLogging near sensitive features (e.g., large sinkholes)

Human Remains / Bones from Cave


Damaged and scarred sinkhole from poor past logging practices


Displacement of soil into vertical solutional openings or epikarst

In BC techniques to assess/inventory forested karst landscapes have been developed, and best management practices for forestry activities on karst are available..

Karst Basics

What Is A Karst System?

As in many issues related to the life and earth sciences, it is important to learn and understand about karst landscapes using a 'systems approach' - whereby a karst system is comprised of:

Interlinked sub-components of the karst geosphere (bedrock and soil)Karst hydrosphereKarst atmosphereKarst biosphere

Continual interchange of materials and energy occur between these sub-components.

Without this approach we are not able to fully understand the processes of karst development or karstification, appreciate the values of this resource, or assess and manage it effectively.

Karst Basics

Forested Karst on Vancouver Island


What Is A Karst Ecosystem?

An ecosystem is the complex group of organisms (plants, animals, fungi and micro-organisms) that live together with their surrounding environment of:

BedrockSoilAirWaterNutrients

An ecosystem can be considered a relatively uniform body of life:

But an ecosystem does vary in space and time as continual (rapid and/or slow) energy and material changes occur due to varying environmental conditions.

Home Experiment #1: Making a Karst Landscape at Home

During this activity you will be making your own karst landscapes using household materials and then use the results for a discussion online.

Equipment & Supplies You Will Need1. A high-side glass or plastic container, e.g., a large jar, small fish aquarium2. Sugar cubes3. Gravel4. Sand5. Water

Instructions1. Fill the bottom of the container with a 5-10 cm layer of coarse gravel, then put in alternating layers of sand

and sugar cubes. 2. Once this is done, slowly add water so that it covers the gravel layer and observe what happens.

Results: Hopefully you get cavities forming in areas where the sugar cubes have dissolved, as well as collapse of the overlying sand

Questions 1. How does this compare to karst landscape formation in terms of surface and subsurface features? 2. What geological materials could this experiment represent?

Variationsa. Try using road salt instead.

Forested Karst on Vancouver Island


b. Use warm/hot water. c. Make a hole in the base of the container to allow water out. d. Use some thin strips of plasticine to act as impermeable bedrock layers.

Post your answers to the questions above to Discussions - M1: Making a Karst Landscape and view the responses of your classmates. Note: You could also take a photograph of your

experiment and attach it to your discussion posting or mail message.

Don't forget to send your Instructor an e-mail message about any concerns or difficulties you have!

What Is The Karst Process?

Karstification is a complex process dominated by chemical dissolution of soluble bedrock along with, to a lesser extent, mechanical erosion:

1. Rain water falling to the surface of the earth absorbs carbon dioxide from the atmosphere.

2. As this rain hits the earth, some of the water becomes further enriched in carbon dioxide as it infiltrates the soil.

3. The resultant water becomes slightly acidic. 4. This slightly acidic water when in contact with limestone (or other soluble bedrock types) causes a chemical

reaction which slowly dissolves the bedrock.5. Existing fractures or crevices in the rock are preferentially widened forming larger cracks allowing for more

water flow and dissolution.6. As the cracks widen, mechanical erosion takes place as loose rock fragments transported by water rub

against the sides of the openings.7. Some of these openings eventually form caves. Many are characterized by or show past evidence of:

o A site of water input (e.g., a sinking stream or swallet), and

o A site of water outflow (e.g., a spring).

Karst Processes

Two views of the Dissolution Process


What Environmental Conditions Are Required For Karst Development?

The most critical requirement for karst is water. Without water there would be no karst or caves!

Water (H2O), primarily in the form of rainfall, is a critical ingredient.Carbon-dioxide (CO2) is another key component as it dissolves in water forming a weak carbonic acid solution (H2CO3) as in Equation 1. This carbonic acid reacts with the solid limestone (predominately CaCO3) to form the soluble ions Ca2+

and HCO3-, as in Equation 2.

Equation 1 = H2O + CO2 H2CO3-

Equation 2 = CaCO3+ H2CO3 Ca2+

+ 2HCO3-

As in any chemical reaction temperature is an important factor, the greater the temperature the faster the reaction.

For example, warm and wet tropical environments, are much better than cold and dry arctic climates for the karst development processes.

Karst Processes

What Are The Primary Controls On Karst Development? A number of factors play important roles in the development of karst:

1. Type and nature of the soluble bedrock2. Thickness and type of soil cover3. Hydraulic head or difference in elevation from top to

bottom of a karst landscape

Some Prime Bedrock Factors for Karst Development Chemical purityFracturingThicknessGeometrical shape

In limestone bedrock, the purer (or higher) the percentage of CaCO3 present, the greater the potential for dissolution.

Fracturing enhances the flow of water through the karst bedrock and provides preferential sites for conduit development.

Karst Spring


Clean White Limestone with Dissolution along Fractures


The thickness of the soluble bedrock unit as well as its geometrical shape (e.g., tilted, folded, interbedded) will play key roles in determining the surface and subsurface shapes of karst landscapes.

Karst Processes

What Are The Primary Controls On Karst Development? Soils can play a significant role in the karst processes:

Soils rich in organics (e.g. a forest floor or a swamp) can make rainfall or surface waters more acidic, thus enhancing the dissolution processThick relatively impermeable soils such as compacted glacial till drift cover can protect soluble bedrock types from dissolutionLikewise, glacial tills rich in carbonate material can buffer rainfall or surface water reducing its natural acidity

Hydraulic head (or the elevation change in the topography) provides a mechanism whereby water moves from a higher topographic level to a lower one (e.g., from a mountain to the sea shore).

A soluble bedrock unit that extends all the way from a high elevation to a low elevation (i.e., has a great relief) is likely to have a greater potential for karst development than one that occurs at a uniform lower elevation.

This activity will provide you with an opportunity to review the concepts you have just learned and learn some basic terms.

Forest Floor on Karst

Credit: Tim Stokes

Karst Occurrences

Where Does Karst Occur In The World? Karst occurs throughout the world.

Approximately 15-20% of the land surface is underlain by carbonate bedrock, the most prodigious of the soluble rocks.Of this 15-20%, 7-10% is considered unsuitable for present day karst development due to:

Unfavorable climateBurial with overlying materials, and Low relief (Ford and Williams, 1989)

Some of the most karst-rich regions of the world include:

Southeast Asia

Worldwide Distribution of Carbonate Rocks


EuropeCentral America

Southeast US

Karst Occurrences

Where Can We Find Karst In Canada?

Karst of some form or another can be found in almost all the provinces and territories of Canada. In fact we probably have one of the widest ranges of karst types in the world.

A significant portion of Canada is underlain by limestone, dolomite and evaporate rocks (halite and gypsum). Examples of karst include:

Gypsum karst from Nova ScotiaHalite (or rock salt) karst from SaskatchewanForested carbonate karst of coastal British ColumbiaAlpine carbonate karst of the Canadian RockiesArctic karst of Northwest Territories

Some of our most famous national parks contain spectacular examples of karst such as:

Nahanni - NWTWood Buffalo - NWT (gypsum karst)Waterton Lakes - Alberta Gwaii Haanas - BC

Bruce Peninsula - Ontario

Module Reading

Readings

CRITICALM1 Reading 1 - Chapter 1 of Cave Geology by Arthur Palmer (your textbook). Focus on the sections covering

Karst and Carbonate Bedrock (highlighted in blue) within Canada


cave types, cave science, show caves and cave preservation/stewardship.

This reading is very cave-bias as opposed to karst, but introduces you the wide range of cave types (the ones associated with karst are the solution caves), plus discusses what cave science (speleology) is about, and then gives you some ideas on cave protection and management.

CRITICALM1 Reading 2 - Karstlands. 1995. by William White et al. American Scientist, Volume 83 p. 450-459. (See under Module 1 on homepage)

This is a great overview paper and provides a good overall insight into karst process, karst hydrology and karst ecosystems. This paper is a must! In fact, if you only read one paper in the whole course this is the one!

CRITICALM1 Reading 3 - Assessment of Forest Karst Resources of Haida Gwaii: A Strategic Overview. 2009. by Paul Griffiths and Carol Ramsey. (See under Module 1 on homepage)

This recent publication is a great introduction to the forested karst of Coastal BC. Even though it focusses on the Queen Charlottes (now called Haida Gwaii) everything is relevant to us on Vancouver Island. It has some excellent colour images. If you can read p. 3-8 you will have covered many of the key concepts in Module 1. We will use it again in later modules.

LESS IMPORTANT, BUT USEFUL M1 Reading 4 - Living with Karst by Veni, G et al. American Geological Institute. 2001. (Double Click for link)

This is also an excellent introduction to karst issues, but from a US perspective. Read up to page 23 if you can.

Additional Resources

Of these three external web sites, I would suggest you focus on Web Site #1 and go through it all. Web Site #2 is also interesting, so look at what appeals to you here. Web Site #3 is just for you to quickly scan to give you a broad

look at some of the applied issues related to karst. Web Site 1: Karst in British Columbia, BC Ministry of Forests

This is an excellent web site compiled by the BC Ministry of Forests that provides a great introduction to the distribution and importance of karst in British Columbia. A brochure (from which the web site is based) was used back in 1997 as one of the first public awareness documents informing the people of BC and Vancouver Island about the importance of karst.

Web Site 2: National Park Service, US Department of the Interior

A good site from the US Park Service that covers some of the critical issues regarding why we should be protecting and managing karst landscapes.

Web Site 3: U.S. Geological Survey , Karst Interest Group Proceedings , St. Petersburg, Florida, February 13-16, 2001

This site just gives you a flavor for some of the real problems when dealing with karst covering biodiversity, hydrology and contamination. We will be investigating some of these issues in later modules.

Summary & Wrap-Up

In Module 1, we have covered some of the fundamental issues about karst. Some of the critical points that you should go away with are:

Karst landscapes are three dimensional and should be treated as a system and not a group of individual features. The surface of the karst landscape is linked to the subsurface by conduits and cavities of various sizes.

Karst landscapes hold valuable resources both in terms of hosting unique ecosystems, storing important scientific information and having spectacular recreational values.

Karst are common landscapes around the world, but require careful consideration and management because of their different attributes compared to non-karst landscapes.

In Module 2 we will look at some of the specific surface landforms and features associated with karst systems, and look further into the distribution of karst in British Columbia and Vancouver Island.

Module Words



http://water.usgs.gov/ogw/karst/kigconference/proceedings.htm

http://water.usgs.gov/ogw/karst/kigconference/proceedings.htm

http://www2.nature.nps.gov/geology/caves/tour.htm

http://www.for.gov.bc.ca/hfp/publications/00192/

Karst-specific terms introduced in Module 1 that you should be familar with include:

1. Pseudokarst2. Paleokarst3. Karstification4. Karst System

Module 1 Discussion Questions

Now that you have completed Module 1 you should have a go at Graded Discussion Question #1. For the graded discussion you will be broken up into small groups who will each discuss the question separately, and then one person (the designated group scribe) will post the group's response. Once each group's response is posted the discussion is open to anyone to provide further comment.

Step 1 - In your respective groups discuss the following situation (that is actually base on a real life example).

'You are a member of a Community Board for a small town on Vancouver Island reviewing the plans of a developer who wishes to construct a series of tourist condominiums and townhouses along the edge of a lake. You hear by way of your friend, a geologist, that the area might be underlain by limestone bedrock'.

What karst questions might you have for the developer to ensure that construction proceeds in a safe and environmentally friendly manner?Provide some rationale as to why you might ask these questions.

This group discussion is done online using postings made to the Module 1 discussion forum title 'Q1 - Discussion Groups on Lake Development Case Study'. At the end of your group discussion formulate a group response.

Step 2 - Now that you have a group response, one member should post the response from each group to the Module 1 discussion forum titled 'Q1 - Group Responses to Lake Development Case Study'. Once this post is made anybody else is free to add comments.

Module Self-Test

Remember to work through this Self-Test to check your understanding of: Module 1 - Karst Systems & Processes

To access seff-test click the Self-Test link in Module 1 on the course homepage to begin...

Each correct and incorrect answer contains valuable feedback that should help you understand these new concepts.

Remember: Self-Tests are optional and for the purpose of your self-assessment.Therefore, they are not graded and do not influence your final mark!

Feel free to repeat a Self-Test as often as you need, in order to feel comfortable with the material presented.

GEOL 310 - Module 1

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Transcript of GEOL 310 - Module 1