This essay focuses on conveying your understanding.Extremely common in the Earth’s crust, igneous rocks are volcanic and form from molten material. They include not only lava spewed from volcanoes, but also.

conveying your understanding

Choose ONE of the following two topics (A or B) and write at least two pages of text on it. Diagrams may be added to aid your explanation, and this is a good way of conveying your understanding. This is worth 20% of your final exam grade.   1A. Describe in detail the thinking and observations by which the relative sizes and distances of the Earth, the Sun, and the Moon were first estimated. OR 1B. Explain in detail how we use the ratios of stable and radiogenic isotopes to date when an igneous rock cooled to the point at which crystals formed.

There are three basic types of rock: igneous, sedimentary, and metamorphic.

Extremely common in the Earth’s crust, igneous rocks are volcanic and form from molten material. They include not only lava spewed from volcanoes, but also.

Rocks like granite, which are formed by magma that solidifies far underground.

Typically, granite makes up large parts of all the continents. The seafloor is form of a dark lava called basalt, the most common volcanic rock. Basalt is also found in volcanic lava flows. Such as those in Hawaii, Iceland, and large parts of the U.S. Northwest.

Granite rocks can be very old. Some granite, in Australia, is believe to be more than four billion years old. Although when rocks get that old, they’ve been altered enough by geological forces that it’s hard to classify them.

Sedimentary rocks are form from eroded fragments of other rocks or even from the remains of plants or animals.

The fragments accumulate in low-lying areas—lakes, oceans, and deserts.  And then are compress back into rock by the weight of overlying materials. Sandstone is form from sand, mudstone from mud, and limestone. From seashells, diatoms, or bonelike minerals precipitating out of calcium-rich water.

Fossils are most frequently found in sedimentary rock, which comes in layers, called strata.

Metamorphic rocks are sedimentary or igneous rocks that have been transform by pressure, heat, or the intrusion of fluids. The heat may come from nearby magma or hot water intruding via hot springs. It can also come from subduction. When tectonic forces draw rocks deep beneath the Earth’s surface.