Premium

What Are Batholiths and Stocks

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

No ratings yet

Just this resource

$1.50

One-time purchase

Best value

Unlock everything

$49.99$29.99/yr

40% off until Aug 1 — 6,000+ resources

Unlock above to use these actions

Format: Interactive (Online), Printable (PDF)
Grades: 678
Subjects: scienceela
Standards: MS-ESS2-1
Languages: English, Spanish

Send Feedback / Report an Issue

What's included

Reading passage

Reading comprehension

Audio narration

With word word highlighting

Comprehension quiz

Auto-graded

Writing activity

Open-ended response

Glossary & flashcards

Vocabulary practice

Differentiated version

Adapted for varied levels

Spanish translation

Bilingual support

About this reader

This comprehensive middle school science reading passage explores batholiths and stocks, two types of massive granite intrusions that form deep beneath Earth's surface. Students will learn how these plutonic rock formations develop when magma cools slowly underground, creating the cores of mountain ranges. The passage explains the difference between batholiths (large, extensive intrusions covering over 100 square kilometers) and stocks (smaller, dome-like intrusions). Through clear explanations and real-world examples like the Sierra Nevada batholith and Stone Mountain in Georgia, students discover how erosion gradually exposes these geological features at the surface. The content aligns with NGSS standard MS-ESS2-1, helping students understand Earth's systems and the rock cycle. Audio-integrated lessons support diverse learners, including English Language Learners and students with different reading abilities. This resource includes differentiated passages, Spanish translations, vocabulary glossaries, comprehension activities, and graphic organizers to reinforce understanding of igneous rock formation and geological processes.

Written by Workybooks TeamPublished by Workybooks

Sample passage and quiz content

CONTENT PREVIEW

Volcanosed — A schematic geological cross-section of a sequence of sedimentary rocks that are later intruded by igneous rocks accompanied by volcanic activity. Image by United States Geological Surveyderivative work: Hardwigg/ Wikimedia Commons

Deep beneath Earth's surface, massive bodies of molten rock called magma sometimes cool and solidify without ever reaching the surface. When this happens, the magma forms large structures called intrusions. Two important types of intrusions are batholiths and stocks. These geological features play a crucial role in building mountain ranges and shaping the landscape we see today.

A batholith is an enormous mass of igneous rock that forms when magma cools slowly deep underground. To be classified as a batholith, the intrusion must cover an area of at least 100 square kilometers (about 40 square miles). Batholiths are typically made of granite, a light-colored rock with large visible crystals. The large crystals form because the magma cools very slowly, giving minerals time to grow. Batholiths often form the cores of major mountain ranges, providing the foundation for the peaks we see above ground.

The Sierra Nevada mountain range in California contains one of the largest batholiths in North America. This massive granite intrusion extends for hundreds of kilometers and forms the backbone of these mountains. The batholith formed millions of years ago when magma pushed up into Earth's crust but never erupted. Over time, erosion wore away the overlying rock layers, gradually exposing the granite at the surface. Today, famous landmarks like Half Dome and El Capitan in Yosemite National Park are visible parts of this ancient batholith.

A stock is similar to a batholith but smaller in size. Stocks cover less than 100 square kilometers and often have a more dome-like or cylindrical shape. Like batholiths, stocks form when magma cools underground and are usually composed of granite. Stocks may actually be the tops of larger batholiths that extend deeper into the crust, or they may be separate, smaller intrusions. Because they are smaller, stocks are sometimes easier to study than batholiths.

Stone Mountain in Georgia is a well-known example of an exposed stock. This massive dome of granite rises about 250 meters (825 feet) above the surrounding landscape. The stock formed underground about 300 million years ago during a period of mountain building. As millions of years passed, erosion removed the softer rock layers that once covered the granite. The hard granite resisted erosion better than the surrounding rocks, leaving the distinctive dome we see today. This process demonstrates how intrusions can become surface features through the constant work of weathering and erosion.

Both batholiths and stocks are examples of plutonic rocks, meaning they formed from magma that cooled beneath Earth's surface. The slow cooling process is key to understanding these features. When magma cools slowly underground, it has time to form large mineral crystals, creating the coarse-grained texture characteristic of granite. In contrast, volcanic rocks that cool quickly at the surface have small crystals or no visible crystals at all. By studying batholiths and stocks, geologists can learn about the processes that occur deep within Earth's crust and how these processes shape the surface over millions of years.

Interesting Fact: The largest known batholith in the world is the Coast Range Batholith in British Columbia, Canada, which extends for over 1,800 kilometers and contains enough granite to cover the entire state of California with a layer of rock several kilometers thick.

What is a batholith?

A volcanic eruption that forms mountainsA massive intrusion of igneous rock covering at least 100 square kilometersA type of sedimentary rock found in riversA small crack in Earth's surface

How do batholiths and stocks differ from each other?

Batholiths are made of granite while stocks are made of basaltBatholiths form at the surface while stocks form undergroundBatholiths cover at least 100 square kilometers while stocks are smallerBatholiths cool quickly while stocks cool slowly

What does the term 'plutonic' mean?

Rocks that formed from magma cooling beneath Earth's surfaceRocks that formed from volcanic eruptionsRocks that formed in ocean environmentsRocks that formed from compressed sediments

Why do batholiths and stocks have large visible crystals?

Because they form near volcanoesBecause erosion creates the crystalsBecause the magma cools slowly underground, giving minerals time to growBecause they are exposed to high pressure at the surface

According to the passage, what is the term 'erosion' referring to?

The process of magma cooling undergroundThe formation of crystals in graniteThe process by which wind, water, and ice wear away rockThe movement of tectonic plates

Which real-world example is given as a batholith in the passage?

Stone Mountain in GeorgiaMount Everest in NepalThe Sierra Nevada mountain range in CaliforniaThe Grand Canyon in Arizona

How does erosion help expose batholiths and stocks at Earth's surface?

Erosion creates new rock layers on top of intrusionsErosion pushes the intrusions upward through the crustErosion wears away overlying rock layers, revealing the granite beneathErosion melts the granite so it flows to the surface

What can geologists learn by studying batholiths and stocks?

How ocean currents affect coastlinesHow processes deep within Earth's crust shape the surface over millions of yearsHow animals adapt to mountain environmentsHow weather patterns change throughout the year

True or False: Stocks are always separate intrusions and are never connected to larger batholiths below.

TrueFalse

True or False: Granite forms large crystals because magma cools slowly underground.

TrueFalse