STALAGMITE, STALACTITE

•  If you have every visited a limestone cave, such as the world famous Carlsbad Caverns in New Mexico, you may have noticed some rather unusual rock formations.  Recall that precipitation that soaks through the soil and rocks on land becomes groundwater, stored below Earth’s surface. If the groundwater is located above a limestone cave, drops of water will sometimes find their way through tiny opening and cracks in the roof of the cave. Microscopic particles of limestone from the roof are worn away as the drop of water travels, and the water carries them along with it. Eventually, the water evaporates, leaving the limestone deposit behind. Over time, many drops follow the same path, adding bit by bit to the limestone formation. By the time thousands of years have passed, all the tiny deposits add up to a large stalactite. A stalactite is a pointed rock formation that hangs down from the roof of the cave and points toward the ground.

• If the drop of water falls to the ground before it evaporates, the limestone deposit starts to build from the floor of the cave upward instead. Following a similar process, drop after drop adds to the formation over many years. When the deposits occur on the floor of the cave pointing up instead of on the roof of the cave pointing down, the limestone formation is called a stalagmite. Rarest of all the cave formations occur when a stalactite and an stalagmite form separately over time, but then meet in the middle and fuse together. This kind of formation is known as a single column.

• Located in the Guadalupe Mountains of New Mexico, the vast 46,766 acre collection of caves known as Carlsbad Caverns is home to some of the  most amazing stalactites and stalagmites on Earth. The caves were discovered in 1901, when a large formation of bats flying upward from the caves was mistaken for smoke. Cowboy Jim White went to investigate, and discovered the amazing rock formations. He photographed them, and visitors began to come from all over the world to see their natural beauty. In 1995, Carlsbad Caverns was named a World Heritage Site by the United Nations Scientific and Cultural Organization.

 Name:__________________________________

Answer the following questions based on the reading passage. Don’t forget to go back to the passage whenever necessary to find or confirm your answers.

1.  In your own words, explain how a stalactite forms:
2.  Explain how a stalagmite differs from a stalactite.
3. Why do you think that the caves at Carlsbad Caverns remained undiscovered for many years.
4.  What mistake led to the discovery of the caves?
5. Why do you think Carlsbad Caverns became so popular with tourists?