Geography True/False

Basaltic magma is believed to originate from partial melting of granitic crust.

FALSE Baslatic magma has a composition nothing like granite.

Magma consists of entirely molten silicates.

FALSE.

Active volcanoes somewhat like those found on Earth have been discovered on all of the inner planets, including the Moon.

FALSE. Active volcanoes have not been found on any other planets.

Metamorphic rocks can be formed from igneous or sedimentary rocks, but not from previously metamorphosed rocks.

FALSE. As metamorphic grade increases, the rocks already metamorphosed continue to recrystallize.

Clay minerals are important constituents of volcanic rocks erupted at high temperature.

FALSE. Clay minerals are stable at LOW temperatures and pressures. They're important in SOILS.

Plates containing continental crust move down into the asthenosphere at deep-sea tenches and are consumed.

FALSE. Continental crust is too buoyant to move down into the asthenosphere.

The ocean floor is smooth and nearly featureless because is has been slowly buried by falling sediment over billions of years.

FALSE. Deep-sea trenches and ridges show MORE RELIEF than that found on the continents.

Earth's atmosphere is made mostly of oxygen (O2), the same compound needed for life.

FALSE. Earth's atmosphere is mostly made of NITROGEN and is quite different from other planets.

Minerals have different melting points that depend on their compositions. In the presence of water, feldspar has a higher melting point than olivine.

FALSE. Felspar is a FELSIC mineral and has a lower melting pint than the MAFIC mineral olivine under these conditions.

One of the most significant features of the continents is the young, folded mountain belts that are typically found in the central interior regions.

FALSE. Folded mountain belts are usually on the CONTINENTAL MARGINS.

Andesite has the same composition as granite but has an aphanitic texture.

FALSE. Granite is more silicic than andesite.

Although gravity acts at all times at Earth's surface, its effects are trivial because the force is so small.

FALSE. Gravity plays a tremendous role in almost all geologic systems. Causes water to flow downhill, plates to subduct, convection of fluid outside and side the planet.

Most plate boundaries are associated between oceans and continents.

FALSE. Most plate boundaries have nothing to do with boundaries between oceans and continents.

Most precipitation occurs on the land and then flows back to the oceans in streams, glaciers, and groundwater.

FALSE. Most precipitation falls back into the ocean.

Most volcanic activity occurs at convergent plate boundaries where one plate is subducted underneath another.

FALSE. Most volcanic activity occurs at divergent plate boundaries such as the mid ocean ridge. They just aren't obvious because their eruptions occur far below the surface of the ocean.

Quartz and feldspar are considered to be magic silicate minerals because of their chemical composition.

FALSE. Quartz and felspar are FELSIC minerals; they are poor in iron and magnetism.

Rhyolite has the same composition as granite but doesn't contain quartz.

FALSE. Rhyolite definitely contains quartz.

Conglomerate, silstone, sandstone, and shale have increasingly smaller grain sizes.

FALSE. SANDSTONES HUGE

A "sequence" is several sedimentary rck formations bounded by layers of volcanic ash that allows them to be radiometically dated.

FALSE. Sequences are usually bounded by erosion surfaces from an important interpretive elect in the rock record.

The most abundant element in the Earth's crust is silicon (Si).

FALSE. Silicon is the second most abundant element. Oxygen is the first.

All sedimentary rocks are transported or deposited in water.

FALSE. Some are done by windblown sediment.

Great volumes of limestone are the most important rock type deposited in a rivers delta.

FALSE. That's CLASTIC SEDIMENTARY ROCKS

The foliation in metamorphic rocks is usually parallel to the direction of compressive stress.

FALSE. The foliation is usually perpidinular to the applied stress.

The largest volcanoes on Earth are composite volcanoes like those found above subduction zones.

FALSE. The largest volcanoes on Earth are SHIELD volcanoes like those formed above mantle plumes.

Earth's oldest rocks are found buried deep in its ocean basis.

FALSE. The oldest rocks are found in the CONTINENTAL SHIELDS.

Crystalline rock indicates a faster rate of cooling than occurs in glassy rock.

FALSE. The opposite is true. A rock that cools quickly doesn't have time to form huge crystals but crystalline is slow and forms big ones.

The rocks on the ocean floor have been deformed by extensive compression.

FALSE. The rocks of the ocean floor show almost NO COMPRESSIONAL DEFORMATION.

There are only two major types of plate boundaries- divergent (where plates move apart) and convergent (where plates move toward one another).

FALSE. The third type is Transform boundaries where plates slide past one another.

The cooling of basalt often produces vertical fractures due to shrinkage, and results in hexagonal prisms of rock. These fractures are called pressure ridges.

FALSE. They're called COLUMNAR JOINTS.

Most geologic systems are closed. That is, they cannot exchange energy or mass with their surroundings.

FALSE. They're mostly open and readily exchange energy and mass with their surroundings. A river system and how is gains and loses energy as it interacts with the environment.

Large-scale cross-bonding is the most common type of sedimentary structure.

FALSE. This happens in EOLIAN SANDSTONES which aren't the most common type of rock.

Heat from inside Earth is the major source of energy that drives the hydrologic system.

FALSE. This heat comes form the Sun and is formed by nuclear fusion.

Because sedimentary rocks form at low temperature, they are rarely related to important natural resources.

FALSE. as hell

Mylonitic textures are dominated by large grains that grew at elevated temperatures and pressures.

FALSE> Mylonites are dominated by grains destroying shearing.

Regional metmorphasism would be best developed below a lava flow.

False. Lava may cause a little but regional tectonic processes covers much more space.

The silicon ion has a positive charge of 4, and oxygen has a negative charge of 2. This, the ion group SiO4 is electrically balanced and has no charge.

False. The SiO4 unit has a net charge of -4.

Weak atomic bonding in one direction in a mineral will result in cleavage.

TRUE. Cleavage is an important physical property and is very useful in distinguishing one mineral from another.

Contact metamorphasim is a local extent and is restricted to zones around igneous intrusions.

TRUE. Contact metamorphism does NOT affect Large areas.

The most abundant group of minerals in Earth's crust is the feldspar group.

TRUE. Feldspars are everywhere in Earth's crust.

Graded bedding is a type of stratification commonly produced on the deep ocean floor by turbid currents.

TRUE. Graded bedding forms in submarine fans.

Pillow basalt is formed when lava extruded under water cools quickly.

TRUE. Lava cooled=pillow

Metamorphism modifies or obliterates most structural and textural features of the original rock.

TRUE. Metamorphism modifies many of the textural features of rocks.

Partial metling is important in the formation of migmatites

TRUE. Migmatites are formed where temperatures become so high that melting begins.

Slaty cleavage is produced by the parallel alignment of minute flakes of platy minerals.

TRUE. Not the same as mineral cleavage.

The difference in elevation of continents and ocean basis represents a fundamental difference in rock density.

TRUE. Oceanic rock is DENSER than the continental rock.

The different states of matter have different densities that correspond to the number of atoms found in a certain volume. The densities of most materials increase from gases to liquids to solids.

TRUE. Only exception is water; ice is less dense that water on the conditions found at Earth's surface.

The color of a finely powdered mineral is called its streak.

TRUE. Rubbing a mineral on a streak plate powders a small amount of it and reveals its streak.

Most of the continents consist of areas we call the stable platforms that are covered with sheets of sedimentary rocks.

TRUE. Stable platforms make up large areas of the continents.

The mineral composition of a metamorphic rock provides a key to estimating the temperatures at which the rock recrystalilzed.

TRUE. The minerals inside form at equilibrium with the environment and tell us about that ancient environment.

Though common on Earth, liquid water in uncommon on the surfaces of other inner planets- Mercury, Venus, the Moon, and Mars.

TRUE. The presence of abundant liquid water on Earth makes it unique in our solar system.

Sedimentary rocks cover approximately 75% or the surface of the continents, and therefore, most of the landscape is formed in sedimentary rocks.

TRUE. They're the most common rocks found at continents surface.

The materials in a system change spontaneously to reach and maintain equilibrium.

TRUE. This is one of the fundamental laws of nature.

An equilibrium state is usually one of lower total energy.

TRUE. This is one of the laws of thermodynamics.

The mesosphere, asthenosphere, and the part of the lithosphere below the crust are all part of the mantle.

TRUE. While these layers are very different PHYSICALLY, they are the same CHEMICALLY.

Hornfels is a fine-grained, nonfoliated metamorphic rock that commonly forms by contact metamorhasism around igneous intrusions.

True. It takes time.

Peridotite is composed almost entirely of two minerals, olivine and pyroxene, with lesser amounts of CA-plagioclase.

TRUE.

Some sedimentary rocks form by precipitation of ions dissolved in water.

TRUE.

The basic source of energy for the tectonic system is heat from inside Earth, much of which is generated by radioactive decay.

TRUE.

The tectonic system is a type of large-scale convection that involves the solid Earth.

TRUE.

If the hydrologic system were interrupted and water did not return to the oceans by precipitation and surface runoff, sea level would drop by about 1 m per year.

TRUE. A vast amount of water is evaporated from the ocean each year.

Andesite volcanoes occur most frequently at convergent plate margins.

TRUE. Andesite volcanoes are the exception- most volcanoes occur at divergent plate boundaries.

Clastic rocks are formed from fragments of other rocks.

TRUE. CLASTIC....Eclastic-fragemnts of other rocks.

Calcite is a non-silicate mineral that is easily dissolved in natural waters.

TRUE. Calcite is a carbonate mineral, and its dissolution is an important geological process.