A layer of sandstone is found on top of a layer of limestone in a geologic cross section. What does this tell you about how the sea level changed in that area?

I know how metamorphic rocks are formed but how are metamorphic rocks formed into other metamorphic rocks?

Check these sites.

http://www.fi.edu/fellows/fellow1/oct98/expert/limestone.htm

http://geology.about.com/library/bl/images/blsandstone.htm

http://www.bobspixels.com/kaibab.org/geology/gc_layer.htm

http://en.wikipedia.org/wiki/Metamorphic_rock

To understand how the layer of sandstone on top of limestone can provide insight into sea level changes, we need to consider the process of sedimentation.

1. Sedimentation: Sedimentary rocks like sandstone and limestone are formed through the accumulation and compaction of sediments. In marine environments, the primary source of sediment is the shells and skeletons of marine organisms. These accumulate over time and, with the help of minerals and pressure, turn into rock layers.

2. Sea Level Changes: The positioning of sandstone on top of limestone suggests a change in sea level.

- If the sandstone layer is above the limestone layer, it indicates that the sea level was rising. As the sea level increased, the sand particles carried by waves and currents were deposited on top of the already existing limestone layer.

- On the other hand, if the sandstone layer is below the limestone layer, it implies that the sea level was falling. As the sea level decreased, the limestone layer formed first. Then, the sandstone layer was deposited on top of it when the sea level was lower.

That being said, the relative positioning of rock layers can help geologists determine past sea level changes in a particular area.

Regarding your question about metamorphic rocks transforming into other metamorphic rocks, it is important to note that metamorphism occurs under specific geological conditions such as heat, pressure, and chemical reactions.

Metamorphic rocks are formed from pre-existing rocks, which can be sedimentary, igneous, or even other metamorphic rocks. The process generally involves:

1. Burial: Rocks undergo burial, typically due to tectonic forces. The added depth causes increased temperature and pressure.

2. Heat and Pressure: Increased temperature causes minerals within the rock to undergo chemical changes. Pressure, either from the weight of overlying rocks or tectonic forces, can lead to the realignment or recrystallization of minerals.

3. Equilibrium: Over time, the rock adjusts to these new conditions, and minerals within it rearrange themselves, forming new minerals and structures. This process often results in the development of new metamorphic minerals and foliation (layering) within the rock.

It is worth noting that the exact type of metamorphic rock formed depends on the specific geological conditions present during metamorphism, including the temperature, pressure, and rock composition. These factors influence the minerals that can form, the texture of the rock, and the degree of metamorphic transformation.