Story: Jenny and Carlos Get Out of the Rain

Chapter Two: Bat Shows Off the Cave

Jenny switched on the flashlight the bat had discovered. Now they could see in the dark. She and Carlos stared at the underground world in amazement. Strange rocks decorated the cave. Some hung from the ceiling, like icicles. Others, like pointy tree stumps, grew from the floor. Flowery crystals grew from the wall where Carlos stood. Jenny stared at curtains of pinkish stone draped down the walls across from where she stood. Both children were struck speechless in this dark and lovely place.

For the first time, they could see their cave guide. The bat hung upside down by the little claws of his hind feet. He dangled from a ledge on the cave wall. They could see his brown snout and big ears. Dark, glittering eyes stared out from a black mask. A coat of chestnut brown fur made him look warm and cozy in the dark cave. Strangest of all were his paper-thin black-brown wings—folded up close to his body like brown paper napkins.

The children had never imagined anything like this cave. As their eyes got used to the faint light of the flashlight, more and more curious structures appeared. They didn't know where to begin looking.

The cavers I met made maps of the cave. Too bad you two don't have a map, teased Bat.

The children did not think it was a funny joke. But they wondered.

"What's a caver?" they asked.

Oh, they are people who like to explore caves, Bat explained. They wear special clothes and boots. On their heads, they wear helmets with lights. They also carry flashlights. They climb up and down the cave walls with ropes. They act pretty goofy sometimes and laugh a lot. They draw little maps in notebooks.

"I wish we had some caver equipment like that," Carlos said. Many questions were going through the children's minds.

How did this cave get here?

Why didn't anybody at science camp know about this cave?

Was it safe to be here? Would rocks fall on their heads?

Where were the water sounds coming from?

How would they get out of here?

Bat's squeaky voice broke into their thoughts. You see why I wanted to find you the flashlight, he commented. Let me show you around now.

Bat spread his little brown wings. He launched himself from the cave wall and flapped around in circles over the children's heads.

"Hey Bat," Carlos asked, "how do you see in the dark with this sonar you told us about?"

Well, remember the echoes you heard? It's kind of like that. The squeaks you hear—I use those for talking to other bats mostly. I can tell how close something is by making a signal that you humans can't hear—only I can hear it. The signal goes out and hits things—like the wall. Then, an echo bounces back and hits my big ears. If it comes back fast, I know I'm going to hit the wall or something pretty soon—like you and Jenny did back there. So I make a turn. If the echo takes a longer time to come back, I can keep going for a while without hitting something.

"Do you always use sonar?" Jenny asked.

No. I use my eyes when we fly out of the cave in the evening, before it gets really dark. And in the cave, sometimes I forget to use my sonar and I bump into things just like a human. It's embarrassing.

Jenny giggled. "It's like you have two pairs of eyes," she said. Carlos took the flashlight and looked around at the strange rock shapes. He asked Bat how they got there.

Bat flew to a nearby rock hanging from the ceiling. He hung from the ceiling and started to answer. Well . . .

"And why is everything wet?" Carlos interrupted, "I've heard water dripping from somewhere ever since we got in the cave. And somewhere I can hear a stream too."

. . . it took water and stone to make this cave. See the rock all around us? It's called limestone. The cave used to be solid rock. It used to have cracks in it, but the cracks got wider and wider until they turned into caves and tunnels.

"How do the cracks get so big?" asked Jenny.

Water trickles down through the earth above us. Especially when it rains like today. And it rushes through the limestone in underground streams. When the water goes through cracks in the limestone, the limestone dissolves away slowly, because the water has a little bit of acid in it. It's a little sour.

As the limestone cracks get wider, more and more water can flow through the cracks. After a while, the water can become an underground stream.

"You mean water can make rock go away? Like water makes soap go away in the bathtub?" Carlos asked.

Well, I don't know what soap is.

Bat thought for a minute.

I've watched the cave explorers make tea. Sometimes they put sugar in the tea and the sugar goes away. It dissolves. The rocks are like the sugar.

Even hard rocks like limestone dissolve. But in a cave it happens slowly. Over a long time—oh, like twenty-five thousand years—the cracks get bigger and bigger. Some of the cracks turn into tunnels, like the one you just crawled through. After awhile the tunnels get bigger and bigger. Some of them join with other tunnels and we get big cave rooms.

"Did the tunnels dissolve into big rooms like this?" Jenny asked. "Is the rock in this cave still dissolving?"

Oh yes. The rock in this cave is dissolving all over the place. Listen to all that water dripping! The tunnels grow into big rooms. Cave explorers call big cave rooms 'caverns.' Later on, I'll show you a place where the whole ceiling is dissolving away. Eventually, it could become so thin it will collapse. Then it's called a sink hole.

The sound of drips went on. The children couldn't tell which drips were drops or which were the echoes of drops. They wondered how many drops could carve out such a big thing as a cave. Carlos thought it would be even slower than the growth of tree rings they had seen at science camp.

"What about these weird shapes?" Jenny asked. "How do they get here? We don't see these above ground."

The Bat went on. No, you don't, Jenny. It's water again. When water drips through the limestone, it picks up tiny bits of limestone. You know, dissolved in the water, just like sugar in tea. So you can't see it. When a drop hits the ground, the water dries up. The limestone in the water gets left behind—or deposited. A coating of tiny crystals slowly builds up.

Bat looked at the icicle shapes hanging from the cave ceiling. Or down, he added. That's how these strange stones take shape. And it's slow again. It takes thousands of years to make some of these rock shapes.

It's funny, laughed the bat. In one part of the cave, water deposits the crystals. In another place, water dissolves crystals away.

"I don't believe this. Water can't do all this," said Jenny doubtfully. She stepped back to look at the rocks hanging from the ceiling.

"Carlos!" she whispered. "Look there! Shine the light in the water. Something's over there. Look! There's . . . oh, I don't believe it!"

Carlos and Bat moved closer to see what she was talking about.

"Watch out Jenny!" Carlos shouted.

Just in time, Jenny glanced behind her. A small stream was flowing through the cave behind her. It was a fast-running stream, but she had not heard it. Her foot dipped into the stream. Splash!

Jenny yanked her dripping foot out of the water as if she had stepped into a hot campfire.

"Oh no! My foot's all wet," she complained. Carlos shone the flashlight on her as she shook off the wet foot. The worried Bat flapped around in circles.

Suddenly Jenny put her foot down. She stared into the stream.

A silvery white creature glided through the water. Then it darted off like a flash of light, a watery ghost. It disappeared behind a rock.

Oh, hi fish. Bat squeaked. This is Jenny. Sorry she fell in your stream. She won't hurt you.

Bubbles streamed up from the fish, still hiding behind a piece of limestone. "He nudged my foot," Jenny said. "I think he was trying to say hello." The children listened as the bat squeaked excitedly.

I'm glad the fish is back, said Bat. Last year, limestone caved in under a garbage dump on the surface. It caused a sink hole. The garbage and pollution in the sink hole fell into this underground stream. Most of the cave fish got very sick from the poisons in the garbage. This fish was OK because she was laying eggs in a place that didn't get the poison. You can see why troglobites don't like people very much.

"Troglo-whats?" Jenny and Carlos asked at once.

Troglobites, cave dwellers, the bat explained patiently. Don't you humans know anything? The cavers knew the word. They say that troglobites are animals that can't ever leave the cave or live anywhere else. Here we have white troglobite daddy longlegs and salamanders and centipedes. They look different from their surface cousins, but they are close relatives.

Now, many have no eyes, and are pale or white, like Ms. Fish. In the stream we also have some pale white shrimpy creatures and crayfish.

"So why are troglobite fishes white?" asked Carlos.

Carlos, laughed the bat, turn off your flashlight. Can you see any colors?

The cave went dark. "No, of course not," Carlos responded.

Right. Troglobites don't need colors in a cave. So their bodies don't waste energy making colorful skin or scales. Just like they don't need eyes either.

"I liked Ms. Fish," thought Jenny out loud. "All silvery in the stream. She looked like a ghost. I can't remember seeing her eyes."

"Are you a troglobite, Bat?" she asked.

No, I'm a trogloxene—a cave visitor. I spend a lot of my time in the cave— I like it here. But I leave the cave when I want to, especially at night. Troglobites have to stay here. They've changed so much that they can't live up there anymore.

Used to be there were really big trogloxenes, like cave bears. Cave earthworms are cave visitors too. If they wanted to, they could live in your lawn.

"Bat, we must be cave visitors, just like you,"Jenny said.

Carlos laughed. "Yeah. We're trogloxenes, right?"

Now you two are getting silly, the bat said. But you're right, I think.

"Do troglobites find their way around with sonar like you?" Carlos asked.

Oh no. Ms. Fish can't see but she can feel things really well with her skin and smell things in the water. In fact, I bet she can feel the water shake when you talk. And crickets have really, really long feelers, he said. They can feel and smell you coming long before you can spot them.

Are there any other kinds of animals in the cave? asked Carlos.

Why yes—the troglophiles, the cave lovers. These animals, like some kinds of cave spiders, could live above, but they spend their whole lives in a cave instead. They like cave life.

By this time they were walking through the tunnel. Carlos was thinking about cave animals, not paying much attention. He certainly wasn't paying attention to everything being so slippery—the moldy rocks on the cavern floor, the slimy cave walls, and oozing mud in the tunnel.

Carlos suddenly slipped and fell back. The flashlight banged on the wall and clattered down on the rocks below. Light flickered for only a moment on the cave wall.

"Oh no!" cried Carlos, feeling around in the dark. The light died. The cave was lost again in thick darkness. Even the bat flapped in surprise.

For a moment, Jenny imagined that she had become a troglobite. Had she turned white? Were long feelers growing out of her head? Just to make sure that she was still a normal human, she reached up to her face. Yes, she still had eyes, but they were eyes that could not see. She had no feelers to guide her through the tunnel.

My ears! Jenny thought. Without my ears and my hearing, I could be lost forever in this cave!