How does sedimentary rock turn into metamorphic

How are sedimentary rocks formed and what are some examples? What types of rocks contain fossils? What types of rocks can become sedimentary rocks? See all questions in Types of Rocks. Skip to content Chapter 3 Intrusive Igneous Rocks. Exercise 3. Previous: Chapter 3 Intrusive Igneous Rocks.

Next: 3. Share This Book Share on Twitter. Regional metamorphism usually produces foliated rocks such as gneiss and schist. Dynamic Metamorphism also occurs because of mountain-building. These huge forces of heat and pressure cause the rocks to be bent, folded, crushed, flattened, and sheared.

Metamorphic rocks are almost always harder than sedimentary rocks. They are generally as hard and sometimes harder than igneous rocks. They form the roots of many mountain chains and are exposed to the surface after the softer outer layers of rocks are eroded away.

Many metamorphic rocks are found in mountainous regions today and are a good indicator that ancient mountains were present in areas that are now low hill or even flat plains.

Metamorphic rocks are divided into two categories- Foliates and Non-foliates. Foliates are composed of large amounts of micas and chlorites. These minerals have very distinct cleavage. Foliated metamorphic rocks will split along cleavage lines that are parallel to the minerals that make up the rock.

Slate, as an example, will split into thin sheets. Foliate comes from the Latin word that means sheets, as in the sheets of paper in a book. Silt and clay can become deposited and compressed into the sedimentary rock shale.

The layers of shale can become buried deeper and deeper by the process of deposition. Deposition is the laying down of rock forming material by any natural agent wind, water, glaciers over time. Because these layers are buried, temperatures and pressures become greater and greater until the shale is changed into slate. Slate is a fine-grained metamorphic rock with perfect cleavage that allows it to split into thin sheets. Slate usually has a light to dark brown streak.

Slate is produced by low grade metamorphism, which is caused by relatively low temperatures and pressures. Slate has been used by man in a variety of ways over the years.

One use for slate was in the making of headstones or grave markers. Slate is not very hard and can be carved easily. The problem with slate though is its perfect cleavage. The slate headstones would crack and split along these cleavage planes as water would seep into the cracks and freeze which would lead to expansion. This freeze-thaw, freeze-thaw over time would split the headstone. Today headstones are made of a variety of rocks, with granite and marble being two of the most widely used rocks.

Slate was also used for chalk boards. I used the number the natural log of 2 0. You can actually plot the curve shown above with a hand calculator. Radioactivity behaves somewhat like popcorn as describe above. There are unstable isotopes of certain elements. These " parent " elements break down into other " child" elements by shedding particles from the nucleus. The rate at which this occurs depends only on the number of atoms around, so it follows exactly the same function as that described above.

We can plot the numbers of parent and daughter atoms as we did for unpopped and popped kernels of popcorn:. The decay constant of a particular parent can be measured in the laboratory by counting the number of times particles decay per second.

If the decay constant of the parent is known, the age of a particular rock sample can be determined by comparing the ratio of parent to child, assuming there was no child in the sample to begin with, and none has been lost in the mean time. Decay rate is related to the half-life as you saw above. All radioactive elements decay in the same way, just some take a long time and some decay very rapidly.

For a material to be useful to geologists, it has to have a half-life on the order of geologic processes and be around. Here is a list of commonly used isotopes and their half-lives:.