Understanding Icebergs The story of the iceberg that sank Titanic began about 3000 years ago. Snow fell on the icecap of Greenland; the snow never melted. Over the course of the next 40 -­‐50 years, it was compressed into ice and became part of a glacier – a river of ice. Due to its enormous weight, the glacier flowed toward the sea at a rate of up to 65 feet per day. Like the snow that formed it, the glacier ice was fresh water ice. When the glacier reached the sea, huge chunks or slabs were weakened and were broken off by the action of rising and falling tides. One of these became Titanic’s iceberg. The iceberg slowly made its way down the coast of Greenland through Baffin Bay and the Davis Strait into the Atlantic Ocean. Most icebergs melt long before reaching the ocean. One estimate is that of the 15 thousand to 30 thousand icebergs produced yearly by the glaciers of Greenland, only 1% (150 – 300) make it to the Atlantic Ocean. Once an iceberg reaches the “warm” water (32 -­‐
40 degrees Fahrenheit) of the Atlantic, it usually lasts only a few months. Very few icebergs are found south of the line 48 N latitude. Titanic’s iceberg collision took place at approximately 41 degrees 56’ degrees N latitude and 50 degrees 14’ degrees W longitude. About 7/8ths (87%) of an iceberg is below the water line. No one is exactly sure how large Titanic’s iceberg was, but according to eyewitness reports it was approximately 50 to 100 feet high and 200 to 400 feet long. It was tall enough to leave ice chunks on one of Titanic’s upper decks. Iceberg Statistics: Icebergs come in range of sizes and shapes. •
•
•
•
•
•
growlers-­‐ less than 3 feet high and 16 feet long bergy bits-­‐ 3 – 13 feet high and 15 – 46 feet long small-­‐ 14 – 50 feet high and 47 – 200 feet long medium-­‐ 51 – 150 feet high and 201 – 400 feet long large-­‐ 151 – 240 feet high and 401 – 670 feet long very large-­‐ anything over 240 feet high and 670 feet long Taken from Titanic Science Created by Miss. Roberta Clarke, 7th Grade ELA Teacher, Mt. Savage Middle School
Page 1 Understanding Icebergs The expression "just the tip of the iceberg" is often used to describe a situation where what you see isn't all you get. The same goes for real icebergs! Icebergs can project 7-­‐9x more underwater than they do above water. Because most of the underwater iceberg is unseen, it poses a risk for sailors and navigators. Since the tragedy of the RMS Titanic in April 1912, an organization known as the International Ice Patrol was founded to monitor icebergs in the Atlantic Ocean and report their movements for Materials: safety reasons. Making an Iceberg Procedure: (Steps 1 and 2 will be prepared by teacher ahead of time) 1. Fill a balloon with water until it is approximately the size of a grapefruit. 2. Freeze overnight. Students will begin experiment here! 1.
2.
3.
4.
5.
6.
7.
8.
balloon (should expand to the size of a grapefruit) • water • tray of ice cubes • freezer • scissors • ruler • clear aquarium or other clear vessel **optional materials • wax paper • graph paper •
Fill aquarium or clear bowl with cold water. Add ice cubes and stir until they have dissolved to ensure water temperature is cold enough. Take iceberg from freezer and removing the balloon u sing scissors. Place icebergs on flat surface and measure their height. Record measurement here _____________. Place the iceberg in clear container with cold water, and use the ruler to measure to how much ice is above the water. Record measurement here ______________. Determine how much of the iceberg is b elow the water. Record measurement here ________________. Calculate the percentage of the iceberg above the surface of the water (height above water divided by total height x 100 = % above water. Record measurement here. Calculate the percentage of the iceberg below the surface of the water (height below water divided by total height x 100 -­‐ % below water. Conclusion: The article states in the last paragraph that approximately 87% of an iceberg is below the surface of the water. Explain whether or not your findings support this claim. ______________________________________________________________________________
______________________________________________________________________________ Taken from Titanic Science Created by Miss. Roberta Clarke, 7th Grade ELA Teacher, Mt. Savage Middle School
Page 2