Frozen Earth Explaining The Ice Age By R. V. Fodor
ICE The book I chose to read is Frozen Earth: Explaining the Ice Age by R. V. Fodor, the associate Professor of Geology at North Carolina State University. It presents the recent discoveries and history of the ice age in an easy-understanding and accessible way. He first begins with a little background of ice ages. He then talks about glaciers and how they form and act. Then he talks about the different theories of how this happened. He concludes with speaking of the future and the climate it possesses.
Scientists have discovered that in the past million years, glaciers have covered the Earth's surface on several different occasions. There have been several "ice ages" in the Earth's past, and twenty thousand years ago was Earths most recently recorded. Large blankets of ice covered a large majority of land, …show more content…
forcing man and animals southward.
Much of North America was under ice. Seven-thousand years ago the glaciers had melted off and that marked the end of it. Because of the glaciers being such ancient history it is hard for scientists to obtain and interpret data. The study of glaciers and the ice age is relatively new. In Switzerland around 1800, rocks attracted geologists in developing the first ideas of the ice ages. They wondered why large smooth boulders, called erratics, were lying out of place in fields and forests. Charles Lyell argued that icebergs had placed them there. Two other scientists stated that the boulders in the valley floors were similar to those found in the glaciers of the Alps. Louis Agassiz, a Swiss scientist, proved that ice could do this. He showed other scientists of places where large
moving ice sheets had scratched and carved the surface of valley walls and floors. He was finally able to prove to the scientists that there had been an ice age. All of many doubts that ice sheets could occupy such large areas of land, were silenced after an expedition to Greenland in 1852. Furthermore, in the 1850s scientists proved that there had been more than one period of colder climates followed periods of warmth. It was believed by the twentieth century that up to four ice ages had occurred during the last million years.
Glaciers are large masses of ice. The north and south poles of the globe are covered with snow and ice year-around. These areas with year-around snow are said to be above the snowline. The elevation of a snowline above sea level varies depending on the amount of heat present and the amount of snowfall a certain area receives. Ice glaciers form not only from the freezing of water but also by compaction. The best example of this is; when you balled up some snow when you were a kid and compressed it into a snowball to throw at your friend. Over hundreds of years of built up snow, glaciers form and begin to grow slowly down hill like molasses. These glaciers move from a few inches a day to rarely a couple yards a day. There are glaciers on every continent except Australia. There is actually a glacier the size of the entire United States in Antarctica. In some places it is deep as one mile! An interesting fact about glaciers; there is enough ice in the world to cover all the land in the world and the sheet would be 400 feet deep! They move like rivers through valleys. The top portion of glaciers moves faster than the bottom portion that scrapes and drags on the surface. Scientists discovered the speed of a glacier at the top of Mt. Blanc in Switzerland from the tragic burial of an entire climbing team. Fourty-one years after, there bodies were found ten-thousand feet away at the foot of a glacier. The bodies had moved eight inches a day. Glaciers move relatively slow, but there has been cases of glaciers moving rapidly out of control. The speed depends on the amount of snow being applied to the source of the glacier. Geologists focus on the rocks and moraines at the mouth of the glaciers that have been scoured and carved by the ice. The evidence is highly informal, but the cause of the ice ages has yet to be discovered. However, there has been many educated theories of why the ice ages took place.
The cause of ice ages must explain why the Earth's climate was relatively colder during periods of the Earth's history. Scientists first looked at the sun for the answers to the ice age. They also thought that volcanoes could have caused the glaciers. When volcanoes erupt, they produce a large area of dark smoke in the air, blocking out the sun. Could many eruptions cause black layers of smog large enough to block out the sun's heat triggering the formation of glaciers? It is possible, but modern scientist have found no evidence of that caliber of volcanic eruptions in the Earth's past. Scientists also looked at the history of sunspots. There was a period in Earth's history of no sunspots, causing the temperature to drop. It was also believed that the sun moved through large areas of dust in the solar system, causing the Earth's climate to change. Both of these theories are possible, but cannot be proved or tested. No explanation for ice ages has received more attention than one based on how the earth travels around the sun and spins on its axis. Hipparchus discovered that the earth's North Pole has not always pointed the same direction in space. What Hipparchus determined 2000 years ago was that the earth's axis "wobbles". The top of the earth moves, drawing an imaginary circle in space. At one time the Earth can tilt away from the sun. This movement is called axial precession and it takes about 22,000 years to complete the circle. What he didn't know is that the wobble effects climate. This set the background for the only theory proven to be a cause of ice ages: the astronomical theory. Johannes Kepler made a striking discovery about how the earth travels around the sun. The earth's orbit around the sun is not a circle, but an ellipse. Two centuries later, a French astronomer Urbain Leverrier, discovered that the shape of the orbit gradually changes over thousands of years. It changes from an ellipse to a circle. The amount of elongation in the orbit at any time is called the orbital eccentricity. In the 1800s, James croll showed that the change in the earth's orbit from high to low eccentricity is approximately every 100,000 years. The orbit is in a period where it carries the earth unusually far from the sun for part of each year. Croll combined the 22,000 year axial precession cycle with the 100,000 year orbital cycle to account for cooler climates, causing the ice age. Through his calculations, he showed that over the period from 80,000 to 250,000 years ago, the Northern and Southern hemispheres had many alternating ice ages and warm periods. His theory appealed to many scientists, but met defeat because some glacial tills were found to be much younger than 80,000 years old. In 1890, Milutin Milankovitch revived the astronomical theory for explaining ice ages. Croll knew of the 22,000 year period for axial precession, but he did not consider that the earth's tilted axis is not fixed at 23.5%. Over time it increases to about 25% and then decreases to 22%. It is called the change in the obliquity of the ecliptic. The complete cycle for the shift takes about 41,000 years. There were now three astronomical events to include in the explanation of ice ages. Milankovitch had no proof for his ideas about climatic changes, however. They were based on his calculations, finding proof was up the geologists. Carbon age-dating showed that his astronomical calculations were not correct. Some data proved there were ice ages during times predicted to be warm by Milankovitch, and warm during times predicted to be ice ages. By 1965, the theory was finished, and reasons for ice ages became a mystery. However, had geologist of the time been able to investigate the seafloor records for ancient climates, hey might have learned that Milankovitch ad his calculations were correct. In 1872, the Challenger set sea to observe data, marking the birth of oceanography. The voyage gave clues to the ocean holding information about the earth's climate history. The discovery lay in tiny floating animals called forams, and teir fossilized remains in seafloor sediments. They took core samples from the sea floor. The scientists discovered that certain "warm" water forams, like those presently in the sea called menardii. They were present in some layers and absent in other layers. The absence of menardii in certain layers indicated that the sedimentary layer accumulated when the waters were cooler than they are today, during an ice-age climate. After that, oxygen-atoms were used to determine the temperature of the water in the past. The data showed that there were several glacial periods over the past 300,000 years. However the different data did not match up and the road to solving the ice'age mystery by using seafloor material seemed to reach a dead end. The quest for solving the mystery did not end however. During the 1960s, John Imbrie and Nicholas Shackleton had developed new theories about forams. They proved the presence of forams depended on more than just the temperature of the water, but also the amount of salt present. A core raised from the Pacific Ocean in 1971 helped prove the theory. Age-dating and oxygen-atom examinations of this core showed that the climate had changed from cold to warm and back again 19 times over the last 700,000 years. Moreover, it showed major changes in climate almost every 100,000 years. That is the core contained a good record of orbital eccentricity affecting climate. Then, in 1973, James D. Hays examined a core from the southern Indian Ocean. Its sediment layers dated back 450,000 years. They also acculated on the seafloor rapidly enough to record detailed climatic changes. Hays found not only the 100,000 year climatic cycle in the core, but also evidence for climatic changes at the times Milankovitch had predicted from information about axial tilt and axial precession. These were 41,000 years and 22,000 year cycles. All the evidence was finally in, and by the mid-1970s scientists could state with confidence that ice ages came and went over the past million years mainly because of changes in climate due to orbital eccentricity, axial tilt, and axial precession. Seafloor sediments record that each of these astronomical cycles works to change the earth's climate. Also many other things, like volcanic eruptions and sunspots, probably contributed, but none can be proven but the Astronomical theory.
I thoroughly enjoyed reading the book. I found it very interesting and wild. I had no clue about ice ages and there background. This was the first I had read of them. Glaciers are amazing things. I couldn't believe the size of some of them and the things they do. I think it would be an interesting and crazy profession to have examining glaciers around the world. I thought the process of how they reached there theories was interesting as well. It was amazing that Milankovitch made those predictions without any evidence. He must have been an extremely chic and intuitive person. It was interesting to learn of the birth of oceanography. I wish I had known that at the presentation on coastal observations a week ago. With this information we can predict ice ages in the future. This was an assignment that I thought was going to be very boring, but I loved the book and found it very interesting. I would recommend reading it to anyone that doesn't know about the ice age.
Scientists have discovered that in the past million years, glaciers have covered the Earth's surface on several different occasions. There have been several "ice ages" in the Earth's past, and twenty thousand years ago was Earths most recently recorded. Large blankets of ice covered a large majority of land, …show more content…
forcing man and animals southward.
Much of North America was under ice. Seven-thousand years ago the glaciers had melted off and that marked the end of it. Because of the glaciers being such ancient history it is hard for scientists to obtain and interpret data. The study of glaciers and the ice age is relatively new. In Switzerland around 1800, rocks attracted geologists in developing the first ideas of the ice ages. They wondered why large smooth boulders, called erratics, were lying out of place in fields and forests. Charles Lyell argued that icebergs had placed them there. Two other scientists stated that the boulders in the valley floors were similar to those found in the glaciers of the Alps. Louis Agassiz, a Swiss scientist, proved that ice could do this. He showed other scientists of places where large
moving ice sheets had scratched and carved the surface of valley walls and floors. He was finally able to prove to the scientists that there had been an ice age. All of many doubts that ice sheets could occupy such large areas of land, were silenced after an expedition to Greenland in 1852. Furthermore, in the 1850s scientists proved that there had been more than one period of colder climates followed periods of warmth. It was believed by the twentieth century that up to four ice ages had occurred during the last million years.
Glaciers are large masses of ice. The north and south poles of the globe are covered with snow and ice year-around. These areas with year-around snow are said to be above the snowline. The elevation of a snowline above sea level varies depending on the amount of heat present and the amount of snowfall a certain area receives. Ice glaciers form not only from the freezing of water but also by compaction. The best example of this is; when you balled up some snow when you were a kid and compressed it into a snowball to throw at your friend. Over hundreds of years of built up snow, glaciers form and begin to grow slowly down hill like molasses. These glaciers move from a few inches a day to rarely a couple yards a day. There are glaciers on every continent except Australia. There is actually a glacier the size of the entire United States in Antarctica. In some places it is deep as one mile! An interesting fact about glaciers; there is enough ice in the world to cover all the land in the world and the sheet would be 400 feet deep! They move like rivers through valleys. The top portion of glaciers moves faster than the bottom portion that scrapes and drags on the surface. Scientists discovered the speed of a glacier at the top of Mt. Blanc in Switzerland from the tragic burial of an entire climbing team. Fourty-one years after, there bodies were found ten-thousand feet away at the foot of a glacier. The bodies had moved eight inches a day. Glaciers move relatively slow, but there has been cases of glaciers moving rapidly out of control. The speed depends on the amount of snow being applied to the source of the glacier. Geologists focus on the rocks and moraines at the mouth of the glaciers that have been scoured and carved by the ice. The evidence is highly informal, but the cause of the ice ages has yet to be discovered. However, there has been many educated theories of why the ice ages took place.
The cause of ice ages must explain why the Earth's climate was relatively colder during periods of the Earth's history. Scientists first looked at the sun for the answers to the ice age. They also thought that volcanoes could have caused the glaciers. When volcanoes erupt, they produce a large area of dark smoke in the air, blocking out the sun. Could many eruptions cause black layers of smog large enough to block out the sun's heat triggering the formation of glaciers? It is possible, but modern scientist have found no evidence of that caliber of volcanic eruptions in the Earth's past. Scientists also looked at the history of sunspots. There was a period in Earth's history of no sunspots, causing the temperature to drop. It was also believed that the sun moved through large areas of dust in the solar system, causing the Earth's climate to change. Both of these theories are possible, but cannot be proved or tested. No explanation for ice ages has received more attention than one based on how the earth travels around the sun and spins on its axis. Hipparchus discovered that the earth's North Pole has not always pointed the same direction in space. What Hipparchus determined 2000 years ago was that the earth's axis "wobbles". The top of the earth moves, drawing an imaginary circle in space. At one time the Earth can tilt away from the sun. This movement is called axial precession and it takes about 22,000 years to complete the circle. What he didn't know is that the wobble effects climate. This set the background for the only theory proven to be a cause of ice ages: the astronomical theory. Johannes Kepler made a striking discovery about how the earth travels around the sun. The earth's orbit around the sun is not a circle, but an ellipse. Two centuries later, a French astronomer Urbain Leverrier, discovered that the shape of the orbit gradually changes over thousands of years. It changes from an ellipse to a circle. The amount of elongation in the orbit at any time is called the orbital eccentricity. In the 1800s, James croll showed that the change in the earth's orbit from high to low eccentricity is approximately every 100,000 years. The orbit is in a period where it carries the earth unusually far from the sun for part of each year. Croll combined the 22,000 year axial precession cycle with the 100,000 year orbital cycle to account for cooler climates, causing the ice age. Through his calculations, he showed that over the period from 80,000 to 250,000 years ago, the Northern and Southern hemispheres had many alternating ice ages and warm periods. His theory appealed to many scientists, but met defeat because some glacial tills were found to be much younger than 80,000 years old. In 1890, Milutin Milankovitch revived the astronomical theory for explaining ice ages. Croll knew of the 22,000 year period for axial precession, but he did not consider that the earth's tilted axis is not fixed at 23.5%. Over time it increases to about 25% and then decreases to 22%. It is called the change in the obliquity of the ecliptic. The complete cycle for the shift takes about 41,000 years. There were now three astronomical events to include in the explanation of ice ages. Milankovitch had no proof for his ideas about climatic changes, however. They were based on his calculations, finding proof was up the geologists. Carbon age-dating showed that his astronomical calculations were not correct. Some data proved there were ice ages during times predicted to be warm by Milankovitch, and warm during times predicted to be ice ages. By 1965, the theory was finished, and reasons for ice ages became a mystery. However, had geologist of the time been able to investigate the seafloor records for ancient climates, hey might have learned that Milankovitch ad his calculations were correct. In 1872, the Challenger set sea to observe data, marking the birth of oceanography. The voyage gave clues to the ocean holding information about the earth's climate history. The discovery lay in tiny floating animals called forams, and teir fossilized remains in seafloor sediments. They took core samples from the sea floor. The scientists discovered that certain "warm" water forams, like those presently in the sea called menardii. They were present in some layers and absent in other layers. The absence of menardii in certain layers indicated that the sedimentary layer accumulated when the waters were cooler than they are today, during an ice-age climate. After that, oxygen-atoms were used to determine the temperature of the water in the past. The data showed that there were several glacial periods over the past 300,000 years. However the different data did not match up and the road to solving the ice'age mystery by using seafloor material seemed to reach a dead end. The quest for solving the mystery did not end however. During the 1960s, John Imbrie and Nicholas Shackleton had developed new theories about forams. They proved the presence of forams depended on more than just the temperature of the water, but also the amount of salt present. A core raised from the Pacific Ocean in 1971 helped prove the theory. Age-dating and oxygen-atom examinations of this core showed that the climate had changed from cold to warm and back again 19 times over the last 700,000 years. Moreover, it showed major changes in climate almost every 100,000 years. That is the core contained a good record of orbital eccentricity affecting climate. Then, in 1973, James D. Hays examined a core from the southern Indian Ocean. Its sediment layers dated back 450,000 years. They also acculated on the seafloor rapidly enough to record detailed climatic changes. Hays found not only the 100,000 year climatic cycle in the core, but also evidence for climatic changes at the times Milankovitch had predicted from information about axial tilt and axial precession. These were 41,000 years and 22,000 year cycles. All the evidence was finally in, and by the mid-1970s scientists could state with confidence that ice ages came and went over the past million years mainly because of changes in climate due to orbital eccentricity, axial tilt, and axial precession. Seafloor sediments record that each of these astronomical cycles works to change the earth's climate. Also many other things, like volcanic eruptions and sunspots, probably contributed, but none can be proven but the Astronomical theory.
I thoroughly enjoyed reading the book. I found it very interesting and wild. I had no clue about ice ages and there background. This was the first I had read of them. Glaciers are amazing things. I couldn't believe the size of some of them and the things they do. I think it would be an interesting and crazy profession to have examining glaciers around the world. I thought the process of how they reached there theories was interesting as well. It was amazing that Milankovitch made those predictions without any evidence. He must have been an extremely chic and intuitive person. It was interesting to learn of the birth of oceanography. I wish I had known that at the presentation on coastal observations a week ago. With this information we can predict ice ages in the future. This was an assignment that I thought was going to be very boring, but I loved the book and found it very interesting. I would recommend reading it to anyone that doesn't know about the ice age.