Igneous rock that cool quickly have small crystals, but slow cooling allows crystals to grow large. Metamorphic rocks show banding, distorted structures and foliation. (Crystal alignment). Mineral properties depend on the internal atomic arrangement and bonding of atoms. Silicon + oxygen = tetrahedron. (The basic structure of silicates.) Isostasy: Earth's crust in a dynamic equilibrium. The crust floats on denser, lower layers. At the mid-ocean ridges new crust is constantly being created. This is known as sea floor spreading. At the ocean trenches the crust being destroyed. It occurs at Earth’s subduction zones. P-waves travel faster through the Earth than S-waves. P-waves can pass through solids & liquids -- S-waves move though solids only. (Liquids absorb S-waves.) You need at least 3 seismometer stations to find earthquake epicenter. In undisturbed strata, the bottom layer is oldest. Intrusion and faults are younger than the rock in which they are found. An unconformity shows where erosion has occurred and a part of the geologic record is missing. Arid landscape usually have steep slopes with sharp angles. Humid landscape are generally smoother with rounded slopes. When in doubt, see if the Reference Tables will help!! Uranium-235 is used to find the age of (date) very old rocks. Carbon-4 is used to find the age of (date) relatively young rocks that contain organic materials. Convection currents in the mantle move Earth’s tectonic plates.
When a rock is broken into smaller pieces, surface area increases