How do index fossils determine the age of rocks?
They don't. Absolute ages are given by dating methods, such as C14, Ar/Ca, OSL, and O16/O18.Fosils only give us relative antiqueness. They tell us whether a rock is older than, or younger than another.How do we know they're younger? That is decided by looking at the rocks themselves! I know, seems contadictory, but it’s really not that hard to understand once you dig into it. The information given by these fossiles serve mostly for when you can't tell which rock is older just by looking at them.You use rocks to determine the relative antiqueness of fossils, and then you use said fossils to determine the relative antiqueness of exceptional rocks.Stratigraphy has a couple of principles. For the effects of this answer, I will cite two.The content of each layer varies vertically, in a way that the most recent stuff always ends on top, and can be identified at considerable distances. This is the faunistic succession principle.Sediments get deposited horizontally until interrupted. Such is the principle of original horizontality.What paleonthologists do is basically look at the layers, and see that Ammonites are on top of Trilobites, therefore, based on those principles, they conclude that Trilobites must be older.Now you have the relative antiqueness of those fossils. Trilobites are older than Ammonites.What do we need that for? Exceptional cases where sedimentary layers end up torn, or at incredible distances where the sedimentary layers themseves don't appear to be exactly the same.If a rock looks like this:And there's a Trilobite in the center and an Ammonite in the outmost layer, you know based on your previous inferences which layer is younger than the rest.And if you find a rock with exactly the same fossil content as another in a distant country, you know that they belong to the same time period.That's what relative antiqueness is for.The example I used is real btw. Trilobites and Ammonites are excelent index fossils of the Paleozoic and Mesozoic period respectively.
Where are the youngest rocks found in the seabed? Where are the oldest rocks found? Why?
The youngest rock in the oceans is found at mid-ocean ridges, where they are formed continually - the oceanic crust.The oldest oceanic crust rocks in the oceans are found in the trenches.They are typically 200 million years old. The oldest one is 280 millions years, in the Mediterranean Sea.Why?Buoyancy puts a threshold on the age of oceanic crust, before it becomes the part of recycling through subduction. As the oceanic crust gets denser with age (cooling), it subducts.On the other hand, the rocks founds on continents are lot older, and some of them, the oldest.Where do we find the oldest continental rocks? And the oldest seafloor?
Place the rock layers in order from oldest to youngest.?
You've left out the picture that is to be used for your problem. The granite is probably the oldest, and then you'd use the stratigraphy to determine the order of events. Here are the laws. http://www4.uwsp.edu/geo/faculty/heffera... Also if the shale, limestone, and sandstone are stacked as SS,LS, S, or S,LS,SS then you've got Marine transgression or regression. Post the picture if you need more.
Which of the following is oldest?
Precambrian Time
Which of the following best describes the Mesozoic period?
A. During this period the K-T extinction took place, which changed many aspects of Earth B. During this period the land on Earth came together to form Pangaea. C. During this period an event known as "The Little Ice Age" took place. D. During this period the oldest rocks and fossils were formed.
Where is the oldest layer in an anticlinal fold located?
To interpret fold structures and map patterns in structural geology (anticlines and synclines), one must first understand some simple geological laws used for relative age-dating of layered or stratified rocks: Law of Original Horizontality and Law of Superposition1 - Original Horizontality: Sedimentary strata or layers are originally laid down (or deposited) horizontally.2 - Superposition: In any given undeformed sequence of sedimentary rocks, the layer on the bottom is older than overlying layers (or, each overlying layer is younger than all underlying layers). Paleontology (biostratigraphy) independently reinforces this law.With these two laws in mind, the pattern of folded, stratified rocks in maps or in cross sections (as viewed in a road cut, a quarry, or in a coastal setting), is more easily interpretable.In anticlines (upwardly bent or deformed layers), the oldest layer in a map pattern or in a cross section is located in the center of the anticlinal structure.In contrast, in synclines (deformed layers bowed downward) the youngest layer is located in the middle or center of the synclinal structureThe geometric relationships discussed above can be compromised by occurrence of faults in an anticlinal or synclinal structure, especially if the offset of the beds along the fault is significant.Here is a cross section of a small anticlinal structure from the Arbuckle Mountains of Oklahoma:Notice in the image above that the lowest layer, the folded layer below the red coat of the geologist, is, based on the Law of Superposition, the oldest layer exposed in the outcrop. As one moves up vertically through the section, each overlying layer is younger in age. At the earth's surface (in the soil zone, and now, try to visualize as if looking down on the surface from above as in a map view), the central or middle part of the fold contains a layer that is older (in a relative sense) than the layers flanking the central part of the anticline (again, all in the soil zone). These younger layers that flank or surround the core of the anticline are to the "above left" and "above right" of the geologist.As an aside, please note the following:a) The crest of the anticlinal structure above is plunging toward the camera (a plunging anticline). Did you notice?b) The core of the plunging anticline is cut by a high angle reverse fault! Can you see this reverse fault and the offset?
What are the chances of becoming a rock star at the age of 40 (or older)?
Pretty slim but I can think of an example which is definitely an exception to the rule.Born in 1940 or 1941, Steven Gene Wold ran away from home and his abusive stepfather aged 13. 5 years previously a mechanic working in his grandfather’s garage going by the name of K.C.Douglas taught the young Wold how to play the guitar. It turned out that Douglas was a relatively well-known blues musician.Wold spent many years living as a hobo, traveling around the US on freight trains and taking on seasonal jobs. He would also earn money busking on the steets.In the early 60s Wold started working as a session guitarist and began producing records for other musicians. In 2006 he released his first album. Then he got his big break.Jools Holland is an English musician who has a highly regarded show on BBC TV which everyone has appeared on and if they haven’t they want to. The then unknown 67 year old Wold appeared on Holland’s New Years Eve Hootenanny show playing blues on a beat-up, three string electric guitar and the star known as Seasick Steve was born.Seasick Steve LIVE ON JOOLS HOLLAND- DOG HOUSESeasick Steve became quite successful in the UK, picking up and being nominated for music awards, selling a lot of records and appearing at numerous music festivals.There are some doubts regarding the authenticity of Wold’s tales about his hobo days with some suggesting that he has embellished his past to appear more interesting and “real”. However, Wold certainly proves that a musician doesn’t have to be young to strike it lucky but he’s definitely not representative of the standard route to musical fame.
Please help me with the following Astronomy Questions?
1. Potassium-40 decays into Argon-40 with a half life of 1.28 billion years. On the Earth, oldest rocks found have ages of 3.8 to 3.9 billion years. If a scientist looked at a total of 64,000 Potassium and Argon Atoms in these rocks, how many would be Potassium and how many would be Argon? 2. The scientific age for the Earth and the Solar system is based on the oldest meteorites, which give a age of 4.65 billion years. In a sample of 64,000 Potassium and Argon atoms from these meteorites, how many would be Potassium and how many would be Argon? 3. Iodine decays into Xenon with a half life of 17.2 million years. If in a dinosaur bone, a paleontologist finds 100 Iodine atoms for every 6300 Xenon Atoms, how old is the dinosaur bone? Please answer them and explain them. Tell me which answer is for which question. Thanks
Which of the following presents the divisions of geologic time in order from largest to smallest?
Try looking the answers up. That'll help.