Questions Flashcards
What is relative dating and how is it used?
Relative dating is the process by which we compare other rocks around a rock to find an estimate of the age of the rock we are trying to find the age for, relative dating is the process of finding relative age except it wont give us the exact age of a rock it might say it’s older than a rock layer though.
The process of relative dating to find relative age of a rock would be igneous intrusions, index fossils, the law of superposition, faults, and the most important comparing other rocks and their layers around them to get a relative age of a rock .
Index fossils: An index fossil is a fossil of an organism that was widely disturbed and existed for a geologically short period of time.
law of superposition: which states that the layer of the rock bottom being oldest and top being youngest will give us the age of a rock. Since a person can happen to rock layers though the law of superposition can only be used for relative age.
Igneous intrusion: Igneous intrusions are formed when molten material beneath Earth’s surface / lava can in this case cool down and cause an igneous intrusion. Sometimes igneous rocks can while there still a form of liquid can seep into the Earth’s cracks and form an igneous intrusion. If a layer is above where it began the layer is younger than the inhouse intrusion.
Faults:
Faults are caused when forces inside of Earth cause movement on the rock it cuts through. They are younger than the layer they cut through.
How does relative dating of fossils differ from absolute dating of fossils?
Relative dating is the process of finding the relative age of a rock and or the fossils inside of them, while absolute dating is the absolute age of a rock and or the fossils inside of them. (Absolute = the actual age of a rock, relative = not the exact age of a rock but more of comparing other evidence around them to give a clue on if something is older or younger than the other thing). Both of these use various processes to find the age of a rock, but both are still very different. Relative dating uses some of the processes known as comparing other rocks around them to get a guess on a rocks age, the biggest one they use to find would be a mix of comparing other layers and also using index fossils and the law of superposition. They will also use faults, igneous intrusions. While absolute dating uses radioactive decay, and a half-life to figure out the rock’s actual fossil and or rocks age.
How do cross-sections of trees determine the age of a tree? What do tree rings tell us about the
past (climate)? Look at the picture on the study guide.
we look at the bar to the left we can see the ages of 4 trees, if we count all of these little spaces we would get the full age of the tree. (These little spaces are also known as the rings on a tree stump) They are also called cross-sections. We do not count the bark nor the pith of the tree, they don’t count as any of the years on the tree. Every little gap is 1 year for a tree. The little gaps are typically the drought seasons of the trees life, they typically get smaller because of dry seasons, very cold weather, not enough carbon dioxide, bad or dry soil, not enough sunlight, microclimate (wind protection), very crowded area with alot of other trees to compete with, and insects. The bigger gaps are the best years of the trees growth, some things that will make a tree have a good year would be: very wet and humid season, hot and or warm weather, great air quality meaning that the air is very sustainable and can give trees the nutrients they need, great soil, great amount of sunlight, a great open space, no harsh winds, and no harmful insects.
Explain how the relative age of faults and intrusions can be determined (think relative age)
We can figure the age of faults when we see all of the layers it has cut through, if a layer isn’t cut it is younger than the fault, if the rock layer was cut it would be older than the fault. This is an example of relative age. Since some form of erosion could potentially happen to the rock layer then more rock layers form above it, there is still a chance that the fault isn’t its actual age. In other words the law of superposition would tell the relative age of a fault. Cross-cutting would be another way to determine the relative ages of faults, it states that if any fault cuts through a rock layer it means that the fault is most likely younger than the layer it cuts through.
For intrusions, intrusions are the youngest when nothing is above where it starts since it is magma drooping into the earth’s layers. If any other rock layer would cover an intrusion they would be younger than in intrusion. That’s how the law of superposition would fall into state here, since the same thing as a form of erosion or weather events could take something away from an intrusion or fault making the law of superposition a way to figure out the relative age of an igneous intrusion.
the law of superposition would only be able to determine the ages of them in relative age.
Be able to look at a rock sample and put the layers in order from youngest to oldest. Refer to the practices that we did as bell work. Look at picture on study guide
The order from youngest to oldest would be E, D, A, B, C. Some things that will come into play would be the law of superposition, faults, and igneous intrusions.
Be able to look at a tree sample to determine the age of the tree, when it began growing, when it was cut down/cored, and what years were good for growth and what years were poor for growth. Review your Tree Ring Lab. Refer to the practices that we did as bell work.
Look at the picture with the tree chart.
Sample
Age of Tree
Year Cut or Cored
Year Growth Began
1
27 years
2001
1974
2
31 years
2005
1974
3
28 years
1995
1967
4
29 years
1987
1958
1976 looks like a drought year for all of the 4 samples. It is smaller and was most likely dry and cold that year. Some others would be 1968, 1970, 1978, 1981, 1982, 1984, 1993, ect. We don’t count the bark and pith of the tree! The darker pieces shown in the photo are some great years of growth for the tree.
Compare and contrast the characteristics of p-waves and s-waves.
P-waves can travel through solids, liquids, and other forms of gases. They stand for primarily waves. S- waves can only travel through solids, they stand for secondary waves. P- waves can travel through the crust, mantel, outer core, and inner core. S-waves can only travel through the crust, and mantle. It cant travel through the inner and outer core since it is a form of liquid in the outer core. Some similarities of these 2 would be that they both are caused by earthquakes, they also can travel through the earth’s interior and can help figure out what earth looks like beneath the surface. P-waves move in a type of way that one part of it compresses in a line and expands after compression, almost in a type of way a worm moves. S-waves move in a type of snake way, almost like side to side motion. P-waves are the first to occur during an earthquake hence the name, they also are a lot faster than S-waves, S-waves move slower and are typically the last to occur. These waves help us figure out what the core is made of, the outer core is made of liquid, the inner core is a solid.
Compare and contrast the outer and inner core of Earth.
The outer core is a liquid made of liquid iron, and nickel. The inner core and outer core are very hard to determine the temperature of since they range from high scales. The inner core is made up from these same materials known as liquid iron, and nickell. The outer core is a liquid, unlike the inner core which is a solid. The outer core will not allow S-waves to pass through them because the outer core is a liquid. Unlike the outer core the inner core is a solid and S-waves could probably pass through them if the outer core wasn’t there. These both have an intense amount of pressure at all times with intense heats too.
What are the 4 layers of earth from outside to inside?
The 4 layers of earth from outside to inside are the crust, mantle, outer core, inner core.
Describe how pressure and temperature change as you move from crust to core.
Pressure will increase the further you / deeper into the earth’s layers, just like how if you were in a body of water the pressure would increase the deeper you get. That’s because more and more mass would be put onto you because you are going deeper into the layers. The temperature would get a lot hotter the deeper you go into earth’s layers as well. Radioactive decay of elements is the main reason for the temperature to increase the deeper you go into earth’s layers.
Explain what happens to continental crust as mountains form and as mountains erode.
We know that the continental crust is far less dense than the oceanic crust making it the top layer of earth for now, since layers are pushing together to form a mountain the continental crust would most likely expand and gain far more mass due to layers colliding with each other. As the continental crust is pushed together the mantle would begin to sink because more and more mass would be put onto it. If the continental crust / the mountain were to get eroded they would both lose mass making the mantle below them begin to rise more and more.
Review Evaluating Earth’s Models Lab, Density Lab, density bellwork and wave demonstration notes.
What 3 processes combine to form convection currents?
The three processes to combine to form convection currents are heating / heat energy, next would be the forces of gravity, lastly changes in any form of density.
