like the present day equatorial bulge, does the earth have a palaeo-bulge?
472569
No, it is my professional geological opinion that there are no 'paleo-bulges'. However, the present one was bigger in the past than it is today. Why? Because the Earth rotated faster when it was formed, and is constantly slowing down very slowly. For example, the day was only 18 hours long about 400 million years ago, the time of the first fish.
182304
great question - I wish I knew more but tides would be different. Also - the day would be shorter. The equatorial regions would be hotter, and the regions further away would be colder. The earth's rotation would be more stable with less wobble.
1150478
It's widely believed in the scientific community that the earth has a liquid mantle (that's where magma/lava comes from) and a solid super-hot iron core.  Good luck digging through that.
839822
This section summarizes advances in our understanding of Venus since 1978 and outstanding problems that require resolution by future missions. The decade following the 1978 report witnessed the acquisition of the first geophysical data relevant to the planet's interior. The Pioneer Venus radar altimeter provided a global topographic map, and radio tracking of the orbiter supplied gravity data over limited regions. In contrast to Earth, Venus's gravity and topography are highly correlated, and interpretations of the combined data may involve mantle and lithosphere dynamical processes peculiar to Venus. The Pioneer Venus magnetometer placed a strict upper limit on any internally generated global magnetic field; the implications of this for the planet's internal structure and theories of the geodynamo are profound and include the possibility that the core is completely liquid. \n\nThe Soviet Venera 15 and 16 radar missions, as well as high-resolution Earth-based radar observations, have revealed a complex tectonic history for the Venus surface. There are unique features visible in these images that could have important implications for internal processes. Although the impact crater record provides a broad constraint on surface ages, limited resolution (1 to 2 km) has prevented identification of the complete record with certainty. The Magellan mission should provide resolution sufficient to characterize the cratering history and to search for a possible relic crater population prior to climatic instability. The mission should also test hypotheses about the timing, style, and rate of surface-modification processes including erosion, possible fossil river beds, volcanic resurfacing, and perhaps plate tectonics. \n\nExperiments to determine major element composition of surface rocks were performed by seven of the Soviet Venera landers. The elemental inventories are all consistent with two types of basalts: high-potassium basalt near a suspected impact feature and tholeiitic basalts in the lowland plains, similar to ocean floor basalts on Earth. \n\nNoble gas abundances in the atmosphere of Venus were measured by the Pioneer Venus and Venera probes, but the data contain serious conflicts and are subject to profound differences of interpretation. The deuterium abundance in the atmosphere was tentatively determined from the 1978 Pioneer Venus data to be 0.016. This elevated value has been a prime driver for the argument that the planet has lost a massive amount of water over the age of the solar system, although an alternative interpretation involving comet impacts is also viable. In addition, the reported abundance of water in the atmosphere has a very peculiar altitude profile when the Pioneer Venus and Venera measurements are combined. Since the water and the deuterium abundances are key quantities in understanding the evolution of the atmosphere and the planet's surface, improved abundances and height profiles are essential. \n\nGlobal changes in the composition of the Venus atmosphere have recently been shown to occur on short time scales, on the order of months or years. Analysis indicates that the global average abundance of SO2 in the visible-part of the atmosphere decreased tenfold between 1978 and 1983, perhaps as result of the recovery of the atmosphere from a massive volcanic eruption. \n\nPioneer Venus provided important information on ionospheric and solar wind interactions, atmospheric thermal structure, zonal and meridional circulation, and planetary-scale waves and tides. The Soviet VEGA balloons collected additional information about the dynamics of the atmosphere of cloud level. \n\nSCIENTIFIC OBJECTIVES\n\nMeasurements from Pioneer Venus, Venera; VEGA, and ground-based investigations have provided a quantitative data base but have also raised fundamental issues concerning the planet's interior, surface, and atmosphere that demand further study. \n\nDetermination of the interior structure is a prim
518888
You may be talking about the Banded Iron Formations (in Minnesota) that formed about 2 billion years ago. This was prior to large amounts of oxygen in the atmosphere, thus the iron was in a reducing environment. That is all I can remember about them, if it is what you are refering to.
348258
The currently-favored theory has to do with Milankovitch cycles:  periodic variations in Earth's axial tilt and orbit that cause it to oscillate between cold and warm epochs.  \n\nThe theory seems to work well, but it has some holes; it can't explain all the ice ages of the past million years, nor why most of the planet's history has been ice free with only a few glacial periods.  In short, there's a lot we don't know about what causes ice ages.
107934
The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle. \nThe plates are made of rock and drift all over the globe; they move both horizontally (sideways) and vertically (up and down). Over long periods of time, the plates also change in size as their margins are added to, crushed together, or pushed back into the Earth's mantle. These plates are from 50 to 250 miles (80 to 400 km) thick. \nThe map of the Earth is always changing; not only are the underlying plates moving, but the plates change in size. Also, the sea level changes over time (as the temperature on Earth varies and the poles melt or freeze to varied extents), covering or exposing different amounts of crust. \nThe current continental and oceanic plates include: the Eurasian plate, Australian-Indian plate, Philippine plate, Pacific plate, Juan de Fuca plate, Nazca plate, Cocos plate, North American plate, Caribbean plate, South American plate, African plate, Arabian plate, the Antarctic plate, and the Scotia plate.
117530
Yes there are. This website tells all about it ---\n\nhttp://www.ivc.edu/geology/ocgeo.aspx
156061
Yes this is true. We know that this happens because of our recent observation but also because crystal formation in rocks shows us that in the past it has switched... Ya strange pockets of magnetic wierdness appear from time to time too(geologially speaking so like over 100,000 years) It all happens really slowly on human time scales but it can (in theory) happen pretty quick. Like over 100's of years. There are plenty of folks watching and taking note. Fortunately, those scientists in the know — paleomagnetists, to be exact — have a ready answer. There is even a really great computer model that they run to test all the variables and options... If it happend over night we'd be in trouble for sure... but it doesn't.
719900
If you’re asking about the research discipline of “planetary geology,” then its origins are rather recent.  Speculation existed about the nature of other planets’ surfaces—e.g., Lowell’s canals on Mars or the oft-envisioned swamps of Venus—but until we started sending spacecraft to explore the worlds and bring back data, such speculations didn’t amount to much of a science.\n\nMost would consider Eugene Shoemaker (1928–1997) the founder of planetary geology; he started the Astrogeology Research Program of the United States Geological Survey in 1961.  Shoemaker’s focus was on asteroids and meteorites, but with increasing quantities of data returned to Earth by missions to Mars, Venus, and other locales, the science grew to encompass many different worlds.\n\nPlanetary geologists study the origin, evolution, and structure of planets and their moons, as well as comets and asteroids.  (The more general term “planetary science” includes disciplines that include orbital dynamics, planetary atmospheres, and so forth.)  Of course, Earth provides a spectacular example of geological processes at work, but many of them (plate tectonics, for example) are unique to our home world.  Nonetheless, interesting analogies exist to the kind of events that may have taken place on other planets, moons, and such, so the challenge is to know what to learn from the well-known terrestrial science of geology and when to keep an open mind.\n\n(At least that’s my best shot.  My background is in astronomy, though, so details of this description might be a little off.)\n\nFor some interesting popular-level articles on the topic of planetary geology, take a look at links on the Geology News website:\nhttp://geology.rockbandit.net/category/planetary-geology/\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
1102973
Not at all. \n\nThe most convincing evidence that led to the acceptance of plate tectonic theory are stripes of magnetized rock that are arranged parallel the mid-ocean ridges and continue all the way to the edges of the ocean basins. These stripes grow progressively older in age as they approach the edges of the oceans, and correspond to past reversals of the earth's magnetic field. Each stripe formed during a period of Earth's history while the magnetic field orientation was steady, and as the field reversed, a new stripe with opposite orientation was formed. Here is a diagram that represents this:\nhttp://www.ucmp.berkeley.edu/geology/tecmech.html\n\nOther types of evidence that changed the paradigm from the old continental drift to plate tectonics was the discovery of mid-ocean ridges, which are volcanic chains larger than the Himalayas that stretch along the center parts of each ocean basin. These are active volcanic zones that are constantly forming new oceanic crust. \n\nPlate tectonics is an especially well proven and robust concept. Evidence of past plate movement is found in all parts of geology, from deposits of oil in both Africa and Brazil that came from the same source, to widespread rocks deposits on different continents that match in composition and character. Biological evidence in the form of fossils adds to the story, and plate tectonics is an important complement to the Theory of Evolution because it explains why some related organisms have had the opportunity to evolve differently in isolation. \n\nAs mentioned, the relatively new science of geodesy, prompted by satellite technology, can now measure the movement of continents precisely, and also can measure the changes in elevation of mountains as they rise. \n\nIf you would like to examine the changes in the earth's continental plates as a result of plate tectonics over time, here is a set of maps that show the movement of the earth's plates in the past and projected into the future:\nhttp://www.scotese.com/
507698
Because of the pull of gravity, however the rotation about it's axis does tend to make it bulge about the equator.
703439
the core of the planet is said to be liquid under pressure, hence volcanoes.  the earth isn't hit with enough meteors etc to much influence the mass of the planet, but as the sea-floor dictates, can change in size.  an example is the two of the main plates, I believe in the area of the pacific rim.  these two plates are moving apart, at times exposing the hot core which pushes its mass into the cracks and cementing the 'spread' of the two plates. \nif the other plates of the planet move likewise, then yes, the world could increase in volume, and give rise to a bigger earth, in lieu of magma escaping from our depths, or by areas of the earth becoming less in depth to the core, like an icecube in a glass of water. \nsci fi of years gone by have mentioned the core in relation to volcanoes.  the implication was that the volcano activity was putting extreme pressure on our core, which if not filled by natural forces, would create a partly filled container under pressure.  the natural result was thought at the time was that the earth would explode or implode.
704239
No, the Earth is much much older.  This is why the Bible is not to be taken literally.  If anything, we were meant to eventually point out these inconsistencies.  The truth is that the dinosaurs existed a long time ago (dragons) and were created to be just another amazing addition to life here on Earth.\n\nThe dinosaurs existed at a time when gravity as we experience it now was attenuated, and we experience much muss less of it.  This is how dinosaurs like the ultrasaur and massive bids like the teratorn were able to walk and fly around without collapsing under their own weight.
695274
It erupts from he center point of the ridge from underneath the crust of the Earth. The center is the oldest point, seeing as how the material flows away from the peak of the ridge. It's like Earth's pressure valve, Hawaii was formed a bit like this.
455077
The actual shape of the Earth today is an OBLATE SPHEROID. It's a kind of sphere but flatter on two opposite sides. These sides are found at the poles.\n\nThe reason why the world is shaped like so is because of the the Earth's rotation. This spinning occured from the time of the Earth's formation up to this day. Centrifugal force tends to throw more matter in its equator than its poles.
54811
According to the US Geological Survey (USGS), the Earth is approximately 4.5 billion years old.\n\nThe articles below discuss the evidence for this estimate.