Karst Landforms

Interactive passage with audio narration, comprehension questions, and printable PDF.

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Format: Interactive (Online), Printable (PDF)
Grades: 5678
Subjects: scienceela
Standards: MS-ESS2-1
Languages: English, Spanish

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Reading passage

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Comprehension quiz

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Vocabulary practice

Differentiated version

Adapted for varied levels

Spanish translation

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About this reader

This comprehensive science passage for grades 6-8 explores the fascinating world of karst landforms, aligning with NGSS standard MS-ESS2-1. Students learn how slightly acidic water, containing CO₂ from the atmosphere and soil, dissolves limestone to create unique features such as sinkholes, disappearing streams, caves, stalactites, and springs. The text integrates scientific thinking by explaining the mechanisms behind these formations, the interactions between surface and subsurface processes, and how karst aquifers supply drinking water but are vulnerable to contamination. Real-world examples like Mammoth Cave and Florida sinkholes illustrate the global importance and hazards of karst regions. The passage includes a glossary, differentiated version, Spanish translations, and a variety of activities such as quizzes, writing prompts, and graphic organizers. Content is audio integrated and designed to develop critical thinking and science literacy in middle school students.

Written by Workybooks TeamPublished by Workybooks

Sample passage and quiz content

CONTENT PREVIEW

"Carlsbad Caverns National Park CAVE2770" by National Park Service Digital Image Archives / Wikimedia Commons (Public domain).

Karst landforms are some of the most distinctive geological features on Earth, seen both on the surface and deep underground. In many regions, sudden sinkholes appear, streams vanish into the ground, or vast cave systems stretch for miles below the surface. These phenomena are all connected by a powerful natural process: the chemical weathering of limestone rock by slightly acidic water. Understanding karst helps scientists explain major landscape changes and manage important water resources.

How Karst Landforms Form: The Power of Dissolving Water
Most karst features develop in areas where the bedrock is made of limestone. Rainwater absorbs carbon dioxide (CO₂) from the atmosphere and soil, forming a weak acid called carbonic acid. When this acid travels through cracks in the limestone, it slowly dissolves the rock. Over thousands to millions of years, this process creates underground openings and enlarges fractures. Surface water can drain into these spaces, sometimes causing streams to disappear entirely underground. When enough rock is removed, the ground above may collapse, forming a sinkhole. In the United States, about 20% of the land surface is karst, and in Florida alone, hundreds of new sinkholes form each year.

Surface and Subsurface Features of Karst Regions
Karst landscapes are rich with unique landforms. On the surface, features include sinkholes, disappearing streams, and springs—where groundwater flows back to the surface. Underground, karst creates caves and caverns, many of which are large enough to explore. Inside these caves, minerals deposited by dripping water form stalactites (hanging from the ceiling) and stalagmites (rising from the floor). Sometimes, these features grow together to make columns. Flowstone covers cave walls with smooth, mineral-rich layers. Famous karst sites include Mammoth Cave in Kentucky, Carlsbad Caverns in New Mexico, Florida’s sinkhole regions, and the dramatic tower karst landscapes of southern China.

Karst Aquifers: Water Supply and Environmental Risks
Karst regions are vital sources of groundwater stored in aquifers. These aquifers provide drinking water for millions of people. However, because water moves rapidly through karst, pollution can spread quickly, making these aquifers highly vulnerable to contamination. For example, chemicals spilled on the surface or leaking from landfills can travel directly into the water supply through sinkholes or fissures. Scientists study karst aquifers to protect water quality and prevent hazards. In developed areas, sinkholes can cause major damage to buildings, roads, and infrastructure.

Karst landforms demonstrate how small-scale chemical reactions, like the formation of carbonic acid, can produce dramatic changes in Earth’s landscape over time. These systems are dynamic, constantly shaped by the movement of water and rock. Studying karst teaches us about Earth’s natural processes and helps us plan for responsible land and water use in the future.

Interesting Fact: The world’s longest known cave system, Mammoth Cave, stretches over 426 miles (686 kilometers) and is still being explored today!

What is the main process responsible for forming karst landforms?

Dissolving of limestone by slightly acidic waterErosion by wind and sandMelting of glaciersMovement of tectonic plates

Which rock is most commonly dissolved to create karst features?

GraniteLimestoneSandstoneBasalt

What is a sinkhole?

A hole formed by wind erosionA depression caused by the collapse of the ground above a caveA hill made of sandA type of mineral formation in caves

How does rainwater become slightly acidic in karst regions?

By absorbing carbon dioxide from the atmosphere and soilBy mixing with salt from the oceanBy freezing and thawingBy passing through volcanic ash

What is an aquifer?

A layer of rock that holds groundwaterA type of cave formationA collapsed sinkholeA river that flows underground

What does the word 'karst' mean in the passage?

A type of mountain rangeA landscape shaped by dissolving limestoneA mineral found in cavesA kind of volcanic rock

According to the passage, why are karst aquifers at risk for contamination?

Because water moves slowly and filters out pollutionBecause water moves rapidly and can carry pollutants directly to the aquiferBecause there are no plants in karst regionsBecause limestone is very hard

If a chemical spill occurs on the surface in a karst area, what might happen?

The chemicals will be filtered out by the soilThe chemicals can travel quickly through cracks and reach groundwaterThe chemicals will stay on the surfaceThe chemicals will evaporate immediately

True or False: Stalactites grow upward from the cave floor.

TrueFalse

True or False: Mammoth Cave is still being explored and is the longest known cave system in the world.

TrueFalse