Unit 3 Rock Type Test (#9 On Your Checklist)

Magma emplacement is not a sedimentary structure because it refers to the process of magma being intruded into existing rock formations, rather than the formation or characteristics of sedimentary rocks themselves. Sedimentary structures are features that form within sedimentary rocks, such as mud cracks, cross-beds, and ripple marks, which are all formed by the deposition and subsequent lithification of sediment.

Coal is formed in a swamp depositional environment. Swamps are wetland areas with high levels of vegetation and organic material. Over time, as the vegetation dies and accumulates, it is buried under layers of sediment. The pressure and heat from the overlying sediment cause the organic material to undergo chemical changes, eventually transforming into coal. Therefore, coal is typically found in areas where swamps once existed.

The correct answer is Igneous, Sedimentary, and Metamorphic. These are the three main groups of rocks based on their formation processes. Igneous rocks are formed from the solidification of molten material, sedimentary rocks are formed from the accumulation and compaction of sediments, and metamorphic rocks are formed from the transformation of existing rocks due to heat and pressure. The other options listed in the question (Basalt, Castic, Crystalized, Intrusive, Magma Based) are either specific types of rocks within these groups or not related to the classification of rocks.

Dynamic metamorphism occurs when rocks grind and squeeze past each other. This type of metamorphism is caused by intense pressure and shear stress, resulting in the recrystallization of minerals and the formation of new rock textures. Contact metamorphism (option A) occurs when rocks are heated by contact with a hot magma body. Impact metamorphism (option C) occurs when rocks are subjected to high pressures and temperatures during meteorite impacts. Regional metamorphism (option D) occurs over large areas due to the combined effects of heat, pressure, and deformation.

At depths of about 50 to 200 km below Earth's surface, the pressure and temperature are sufficient to cause rocks to melt. This is because as you go deeper into the Earth, the pressure and temperature increase, eventually reaching a point where the rocks can no longer maintain their solid state and melt.

Remains or traces of organisms preserved in rock are called fossils. Fossils provide valuable evidence of past life on Earth and can include bones, shells, imprints, or even preserved soft tissues. They help scientists understand the history of life and how species have evolved over time. The correct answer options all refer to the same concept, which is the remains or traces of organisms preserved in rock.

A lahars is not an intrusive igneous body. A lahars is a type of volcanic mudflow or debris flow composed of a mixture of volcanic ash, rock fragments, and water. It is formed when volcanic material becomes saturated with water and flows down the slopes of a volcano or other elevated area. Lahars are not formed through the cooling and solidification of magma within the Earth's crust, which is the process that forms intrusive igneous bodies such as batholiths, stocks, and dikes. Therefore, D is the correct answer.

The increase in temperature with depth in the Earth is called the geothermal gradient.

Igneous rocks are classified based upon their texture and mineralogy. Texture refers to the size, shape, and arrangement of the mineral grains in the rock, while mineralogy refers to the types of minerals present in the rock. By examining the texture and mineralogy of an igneous rock, geologists can determine its origin and formation process.

Glacial meltwater is not a metamorphic agent because it does not cause changes in the structure or composition of rocks. Heat, pressure, and hot water are all examples of metamorphic agents because they can cause rocks to undergo metamorphism, which is the process of transformation of rocks due to changes in temperature, pressure, or chemical environment.