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21

which came first That's actually a very hard question. The most simple answer would indeed be igneous. Here's why: Sedimentary rocks (in the sense of rock cycle) comes from pre-existing igneous or metamorphic rocks, so you need to have had them first. Metamorphic rocks, by definition, are rocks that form from other kinds of rocks (be it igneous or ...


18

It's an interesting question, but in practice I think it's impossible to answer. It's very difficult to measure the rates of many of those processes, and the divisions between rock types can be quite ill-defined (for example, in migmatites). There's no scientific instrument we can point at a chunk of the earth which will tell us "in this region, 29.4 ...


16

There is a technique called "Exposure Dating". Using e.g. cosmogenic nuclides (they are produced in the first metre or so of the surface of a rock which is exposed to cosmic rays, i.e. on the surface of the earth), it is possible to estimate the amount of time that the rock was exposed. With some assumptions, you can get an exposure age of the fracture ...


15

The Earth existed long before there were crustal rocks or a "rock cycle." The idea of the "rock cycle" has prerequisites to even be meaningful. These include: The existence of a crust (both a continental and oceanic crust actually.) Plate tectonics The existence of an atmosphere and ocean. Without all of these, the concept of the rock cycle (as introduced ...


15

Zeolites are very similar to clays, with one key difference. The molecular structure of clays is rather compact. In contrast, the molecular structure of zeolites has tiny molecular-sized holes, and these holes are wont to connect. The result is a porous, tunnel-filled structure at the molecular level. The resulting tunnels make zeolites very good at ...


15

I'm quoting from my old The Penguin Dictionary of Geology by D. G. A Whitten & J. R. V. Brooks, published in 1979. Rock (1) To the geologist any mass of mineral matter, whether consolidated or not, which forms part of the Earth's crust ... (2) The civil engineer regards rock as something hard, consolidated, and/or load bearing, which, where ...


15

Here, you can use this shoddily drawn table.


14

How Japan Filled That Ginormous Sinkhole In Just One Week: The Fukuoka sinkhole measuring 8,700 square feet (808 square meter), 65 foot (20 m) deep: they poured a mixture of soil, water, and cement into the hole—they use more than 7,100 cubic meters of the stuff in all. YouTube timelapse. How To Fix a Giant Sinkhole about the two in Guatemala: The first ...


13

OK, so you've found yourself an interesting rock and you want to know how to identify it. I am going to go ahead and assume that you haven't studied Geology before (apologies if that's an assumption too far). The first thing you can do is to head to your local public library and find a basic "rocks, minerals and fossils" identification book, and try to ...


13

Mountains and rock do decompose or weather into sediment. A basic rock cycle overview shows the possible pathways between all three rock types (igneous, metamorphic, and sedimentary) how one type can be transformed into another. After a rock is weathered into sediment, that sediment can become a rock again. Weathering rates of rock vary widely regional ...


13

the trick is not all isolated rocks are produced the same ways. Of the two in your pictures the first is an old volcanic events; intrusions, dikes, ect. depending on which rock in the region you are talking about. The whole deccan plateau region is full of them, some have been exposed on the surface via erosion. Basically everything else eroded faster than ...


12

One can only speculate based upon a photograph - however they look very much like mineralized fractures. At some time in the past this rock mass may have fractured in response to thermal or tectonic stresses. Fluid may have then penetrated relatively long distances along the fractures into the area and infiltrated shorter distances into the wall rock along ...


12

I usually tend to think that the shorter a definition is the more it introduces ambiguity and errors. So I would just think about your audience and choose an appropriate length (You didn't mention the level you are teaching for). Similar to the definition of life you can offer to your audience characteristics, which some rocks will conform more or less. ...


11

Most sources say that rocks are made of stones. (Or at least that stones are rock fragments.) From the Bing dictionary (definition of stone): hard nonmetallic material: the hard solid nonmetallic substance that rocks are made of. rock fragment: a small piece of rock of any shape shaped rock fragment: a piece of rock that has been shaped for ...


11

The best way to learn about rock types is to handle rock specimens guided by an experienced geologist. By handling rock specimens you get to feel the weight of the rock, its roughness or smoothness or if it feels slippery, soapy, glassy, firm or crumbly. Is it weak or strong? You will also be able to better see the colours in the rock, the sizes of the ...


11

You are looking for a portable XRF. It does (almost) exactly what you said. It sends electromagnetic radiation to the rock (X-rays), which excites electrons in the atoms and when they bounce back they return X-ray of different energies which are detected by the instrument. It looks like this, for example: Using the different peaks you can figure out what ...


10

According to page 86 of Exploring the World Ocean: In December 1989, ODP scientists drilled Hole 801C and recovered Jurassic-age rocks and sediments, about 170–165 million years old, from the Pigafetta Basin in the western Pacific, near the Mariana Islands. Sediments of nearly identical age had been found previously from the Deep Sea Drilling ...


10

Not as far as I am aware. Any dating of the rock would determine the formation age of the rock (dating isn't quite as straight forward as that, and there is a whole science behind what each dating technique actually determines but for simplicity's sake we say it is the formation date) but the fracture plane,where the hand sample has broken away from the ...


9

When learning to distinguish between siliceous and calcareous samples you should use a handlens. Look for quartz, feldspars or micas. Quartz clasts may be frosted, or you may be able to see conchoidal fracture. Calcite will be very soft compared to both feldspar and quartz, and should fail to scratch copper (or at least not scratch it very well, while a ...


9

This is the key: used to be part It is important to look at this from a historical point of view. Up until the 1950s and early 1960s, there was no agreement to how granites form. This became the granite controversy. On the one hand, experimental work showed that granites crystallise from magma, but this magma had to be derived from basalt-like magmas. ...


9

That is a sea urchin (echinoid) or at least part of one. the pattern of plates is fairly distinctive. 2 rows of small plates alternating with 2 rows of large plates. I am not familiar enough with urchin phylogeny to give you species but you might be able ot get it from the biology stack.


8

Since rocks can have magnetic signatures, as is the case with paleomagnetism, can they store past pressures also? Yes, but not directly, and it is very hard to know the exact pressure (in contrast with paleomagnetism where you can actually get a nice number). One way to do it is to simply look at the minerals you have in the rock. Some minerals exist only ...


8

The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by ...


8

I can engage in some educated speculation about what you think you see, but I'm confident you were fooled by the shadows in the image, which are caused by a low sun angle and distorted by the terrain. These are not inuksuit (which is the correct plural of inuksuk). They are all natural, not man-made. Let's point out a few things we know and can see on the ...


8

Even rocks that have lasted for billions of years decompose when exposed to Earth's weather. What you have is indeed granite, but a somewhat decomposed granite, which is treated by geologists differently from the intact, solid stuff. The "crumbly bits" have their own name: grus. Granite is made of crystals of different minerals (mostly feldspar and ...


8

That's amethyst, a violet version of quartz See here


7

Oolites are limestones that are usually considered as in-organic, although they may have bits of shell/etc in them. These form by the precipitation of calcium carbonate around particles (sand, broken shell, etc) with a process comparable to that of an oyster. Some oolite references: http://www.sandatlas.org/2012/09/oolite/ http://en.wikipedia.org/wiki/...


7

Like Michael, I find your question a little unclear, but the crux of it seems to be this: ... does science have to conclude [that a specimen is] just a rock because the composition is entirely from earth minerals? The answer is an emphatic no. There are lots of non-rocks out there, many of them manufactured by the (alleged) intelligence known as Homo ...


7

Yes, this is a granite. It's hard to know exactly which one. A geological map of the area shows the bedrock to be sedimentary rocks, so this piece of granite was transported in the creek from far away (but not too far, otherwise it will crumble completely). If we go further east, for example with this geological map, we find that: To the east, the ...


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