Llamatepeque

GEOLOGY
The principle of original horizontality was also proposed by Steno. It simply states that layers of sediment are generally deposited in a horizontal position. When examining a rock outcrop,if the rock layers are flat, it means they have not been disturbed and the original horizontality is maintained. The principle of cross cutting relationships applies to faults and igneous intrusions.Faults that cause a rock layer to break must have occurred after the rock layer was deposited. Similarly, igneous intrusions cannot cut across or disturb rock layers unless the rock layer wasdeposited before the intrusion occurred.

Geologists work to understand the history of our planet. The better they can understand Earth’s history the better they can foresee how events and processes of thepast might influence the future. Here are some examples:

Geologists study earth processes: Many processes such as landslides, earthquakes, floods and volcanic eruptions can be hazardous topeople. Geologists work to understand these processes well enough to avoid building important structures where they might be damaged. If geologists can prepare maps of areas that have flooded in the pastthey can prepare maps of areas that might be flooded in the future. These maps can be used to guide the development of communities and determine where flood protection or flood insurance is needed.Geologists study earth materials: People use earth materials every day. They use oil that is produced from wells, metals that are produced from mines, and water that has been drawn from streams orfrom underground. Geologists conduct studies that locate rocks that contain important metals, plan the mines that produce them and the methods used to remove the metals from the rocks. They do similarwork to locate and produce oil, natural gas and ground water.

Geologists study earth history: Today we are concerned about climate change. Many geologists are working to learn about the past...