9.29 Stalactites & Stalagmites

Some caves have cool-looking formations called stalactites and stalagmites. Although they grow in different directions and may be different sizes and shapes, they are all formed by the same basic process. In this lesson, you will learn about these formations.

What are Stalactites and Stalagmites?

Imagine climbing deep into a dark, wet cave. When the click of your flashlight switch echoes against the cave walls and there is finally some light, you see strange formations growing from the ceiling and the ground. Have you teleported to some alien planet? No! What you see are stalactites, stalagmites and columns! Let’s take a look at them now.

1. Main Points:

You explore a dark, wet cave and discover natural formations like stalactites, stalagmites, and columns when you turn on your flashlight.

2. Questions:

• Content Analysis: What kind of formations do you discover in the cave?
• Contextual Analysis: What setting is described for discovering these cave formations?

3. Further Discussion:

Why do you think the formations like stalactites and stalagmites are often described as “strange” or “mysterious”?

4. Answers:

• Content Analysis: In the cave, you see “stalactites, stalagmites and columns.”
• Contextual Analysis: These formations are discovered when you are “climbing deep into a dark, wet cave,” and you turn on your flashlight, which brings “light.”

So, isn’t it cool how a dark, mysterious place can hide such fascinating things like stalactites and stalagmites? It’s like the cave is keeping a secret until you shine some light on it! What other secrets do you think the Earth might be hiding from us?

Stalactites

Stalactites are formations that look like icicles and grow down from the ceiling of a cave. They form over time when water slowly drips from cracks in the ceiling, like a leaky faucet. There are minerals dissolved in the water that build up over time as the water drips, eventually forming stalactites.

Some stalactites grow faster than others, but none of them grow very fast. The slowest-growing stalactites have been measured to grow less than an inch every hundred years. In comparison, a baby grows about ten inches from the time it is born until it turns one!

Stalactites Growing from a Cave Ceiling
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The most common type of stalactite is hollow, like a drinking straw. These are called soda straw stalactites. When many stalactites grow close together, they look like the curtains you see on windows.

Not only are most stalactites old, they are easy to break, which is why people aren’t allowed to touch them when they go on cave tours.

1. Main Points:

Stalactites are slow-growing, delicate formations in caves that look like icicles; they are formed by the build-up of minerals in dripping water.

2. Questions:

• Content Analysis: How do stalactites form in caves?
• Contextual Analysis: How slow do the slowest-growing stalactites grow, and how does this compare to a growing baby?
• Socio-cultural Analysis: Why aren’t people allowed to touch stalactites during cave tours?

3. Further Discussion:

If stalactites grow so slowly, what might this tell us about the age of some caves?

4. Answers:

• Content Analysis: Stalactites form “over time when water slowly drips from cracks in the ceiling,” and “minerals dissolved in the water” build up to form them.
• Contextual Analysis: The slowest-growing stalactites “grow less than an inch every hundred years,” while “a baby grows about ten inches from the time it is born until it turns one.”
• Socio-cultural Analysis: People aren’t allowed to touch stalactites because they are “easy to break.”

Isn’t it amazing to think about how patient Mother Nature has to be for these stalactites to form? And remember, you gotta treat them like the old, delicate treasures they are if you ever visit a cave! Would you like to explore a cave one day?

Stalagmites

Stalagmites form and grow up from the cave floor when water drips down from the stalactites on the cave ceiling, which is why they are usually found right underneath them. The minerals in the water build up, just as they do on the stalactites, but this time, they land on the ground and grow upward. The water evaporates, leaving the minerals behind. It takes about the same amount of time for a stalagmite to grow as a stalactite.

Stalagmites Growing Up from the Ground of a Cave
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Stalagmites form various shapes when they grow and have different names. For example, small, rounded stalagmites are called button stalagmites, and stalagmites that look like broken plates that have piled up in a sink are called pile-of-plates stalagmites.

1. Main Points:

Stalagmites are upward-growing formations in caves, typically forming beneath stalactites. They grow due to the accumulation of minerals from dripping water.

2. Questions:

• Content Analysis: How do stalagmites form and grow?
• Contextual Analysis: How does the growth rate of stalagmites compare to that of stalactites?
• Terminology Analysis: What are some specific types of stalagmites based on their shapes?

3. Further Discussion:

What factors might affect the shape that a stalagmite takes as it grows?

4. Answers:

• Content Analysis: Stalagmites form “when water drips down from the stalactites on the cave ceiling” and lands on the ground. The minerals in the water build up, causing the stalagmites to grow upwards.
• Contextual Analysis: It takes “about the same amount of time for a stalagmite to grow as a stalactite.”
• Terminology Analysis: Specific types of stalagmites include “button stalagmites,” which are small and rounded, and “pile-of-plates stalagmites,” which look like piled-up broken plates.

So, whether you’re looking up at stalactites or down at stalagmites, the cave’s subterranean beauty is a testament to the slow yet intricate processes of nature. How fascinating is it that both formations take about the same time to grow but in opposite directions!

Columns

Sometimes, stalactites and stalagmites grow so long that they touch each other and grow together into one big formation. These are called columns. They look like columns you might see on a porch, but they break easily.

Columns Formed by Stalactites and Stalagmites Growing Together
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1. Main points:

Stalactites and stalagmites can grow and eventually touch each other, forming a fragile structure called a column.

2. Questions:

• Content Analysis: What are columns made of?
• Linguistic Analysis: What words are used to describe how fragile these columns are?

3. Further Discussion:

How might the fragile nature of columns affect their surroundings or their role in a cave’s ecosystem?

4. Answers:

• Content Analysis: Columns are made when “stalactites and stalagmites grow so long that they touch each other and grow together into one big formation.”
• Linguistic Analysis: The text says that these columns “break easily.”

Alright kiddos, let’s chat about this. Have you ever tried stacking blocks so high that they nearly touched the ceiling? Well, imagine that happening in nature, with things called stalactites and stalagmites! Except, they are a bit more fragile than your sturdy blocks. What do you think could happen if you touched one of these columns? 🤔

A Little Trick

You might think it’s hard to remember which formation grows from the ceiling and which grows from the ground, but it’s really easy! The word stalactite has a C in it, and so does ceiling. The word stalagmite has a G in it, and so does ground. Good to know!

1. Main points:

The text provides a mnemonic to easily remember that stalactites grow from the ceiling and stalagmites grow from the ground, using the letters “C” and “G” in the words.

2. Questions:

• Content Analysis: What’s the trick to remember which formation grows from where?
• Thematic Analysis: What is the main theme or topic addressed in this text?

3. Further Discussion:

How do you usually remember tricky stuff? Do you have any mnemonics of your own?

4. Answers:

• Content Analysis: The trick to remember is that “The word stalactite has a C in it, and so does ceiling. The word stalagmite has a G in it, and so does ground.”
• Thematic Analysis: The main theme is remembering the difference between stalactites and stalagmites using mnemonics.

Hey gang! 🌟 Ever get confused about which is which between stalactites and stalagmites? I mean, they’re both kinda long words, right? 🤔 The cool part is, there’s an easy-peasy way to remember! Do you have any tricks for remembering other tough things? Maybe for tests or spelling words? 📝

Lesson Summary

Stalactites grow on the ceilings of caves and are formed from minerals in the water that drip from the cave ceilings.

Stalagmites grow from the ground of caves, are usually found right under stalactites and are also formed from the minerals in the water that drip down from the stalactites on the ceiling.

When stalactites and stalagmites grow large enough to touch each other and then grow together, they are called columns.