Notes, summaries, assignments, exams, and problems for Geology

Hydrological Effects

The construction of a dam is usually responsible for profound changes in the hydrology of the stream, both regarding the system of flow and sediment transport.

Changes in Flow Regime

The construction of a dam substantially alters the flow regime upstream since it changes a particular stretch of river with flowing water into an artificial lake. As a result, the formation of the reservoir causes changes in the water table around the lake, these being more or less significant changes, according to the variation of the water level in the reservoir over time. This can cause problems with slope stability periodically immersed in the foundations of buildings near the reservoir, the water supply wells in agricultural areas in the... Continue reading "Hydrological Effects of Dam Construction" »

Study of Earth's Interior

Indirect Methods for Studying the Deep Earth

• Seismic Method: This involves analyzing the echoes of sound waves produced by a small surface explosion. These waves bounce off different layers within the Earth.
• Gravimetric Method: This method detects small variations in the gravitational field caused by the distribution of rock mass deep within the Earth. Light rocks create a negative gravity anomaly, while dense rocks create a positive one.
• Measurements of Isotopes: This allows scientists to determine the exact temperature of the water in which an organism lived.
• Radiometric Dating: This is used to determine the age of a rock sample.
• Study of Meteorites: Meteorites provide valuable insights into the composition of the early

Vaporization: Evaporation and Boiling

To produce vaporization, liquid particles must reach sufficient kinetic energy to overcome the forces holding them together. This allows them to separate and move independently. Vaporization can occur in two ways: evaporation and boiling.

Evaporation occurs at all temperatures but only on the surface of the liquid. It happens more rapidly when temperature increases or pressure decreases. Not all liquids evaporate at the same rate; those that evaporate quickly are called volatile.

Boiling occurs throughout the volume of the liquid but only at a specific temperature called the boiling point. The boiling point is characteristic of each pure substance but depends on pressure (it increases as pressure increases)... Continue reading "Understanding Phase Transitions" »

Understanding Earthquake Magnitude and Intensity

The moment magnitude is determined from an estimate of the area that breaks along a fault plane during the earthquake, the amount of movement or slippage at failure, and the stiffness of the rocks near the focus of the quake.

The intensity of an earthquake is often indicated by the Modified Mercalli Scale, which is a qualitative measure. The intensity of an earthquake is usually displayed on a map.

Seismic Waves Explained

When a fault is generated, the rocks break suddenly and violently, releasing energy in the form of seismic waves.

P Waves

The P waves, also called compressional or primary waves, are the most rapid of the two main types. They can travel through a solid, liquid, or gas. P waves travel... Continue reading "Earthquake Magnitude, Seismic Waves, and Zones" »

Lingual Arch

The lingual arch is a very useful device that is used to stabilize teeth (6-6), maintain anchorage in the jaw, or prevent teeth (6-6) from moving mesially and buccally. It can also widen the incisors and the dental arch.

It is used in mixed dentition (with temporary and permanent teeth) and as a holding arch at the end of treatment.

It is built on metal strips (6-6), adapting hard orthodontic wire (0.8 to 1 mm) in contact with the lingual surfaces. Its union with the band, in this case, is welded.

Nance Button

The Nance Button is used to reinforce the anchorage of the upper molars, stabilize molar groups, rotate molars, and increase the transverse distance between molars.

It is constructed with 1 mm wire, and this goes from one band... Continue reading "Orthodontic Appliances: Types and Uses in Dental Practice" »

Natural Hazards

Natural hazards represent the probability of an area's population experiencing damage or catastrophe due to a natural event. UNESCO defines risk as the probability of human and property loss from natural or human-caused phenomena.

Key Concepts

• Dangerousness of a Natural Process: This estimates the potential of a natural process to cause environmental transformations, regardless of social context.
• Interference: This refers to the degree of interaction between a natural process in a specific area and human activities.
• Damage: This encompasses the types of transformations caused, considering economic, cultural, and production-related impacts.
• Social Catastrophe: This is the actual realization of a risk, measured by the resulting economic

Bending Beams: Design Principles & Applications

Bending beams are primarily used in structures where managing mass distribution and resisting bending forces is crucial. Within a beam subjected to bending, a pair of internal compression and tension forces develops. To improve performance, a higher torque arm (i.e., the height (canto) or width of the beam in the plane of bending) is essential. Therefore, enhancing performance isn't always about increasing the overall cross-section of the piece, but specifically its height (canto), which guarantees an optimal moment of inertia and adequate capacity to resist shear forces. However, this focus on height can sometimes be inconvenient if the prevailing interest is in the functionality of spaces,... Continue reading "Structural Beams, Porches & Timber Truss Wall Systems" »

ITEM 7: Water Resources

Aquifers

Aquifers are layers of porous and permeable rock or sediments that transmit groundwater freely. They tend to be limited, at least in their lower part, by impermeable strata, forming an underground water "store." The area where all the pores are completely filled with water is called the saturation zone, and its upper limit is the water table.

Ecological Flow

Ecological flow, also known as minimum or environmental flow, is the portion of a river's flow that is left in the river after extraction for human use (urban, agricultural, industrial, etc.) to ensure the survival of the ecosystems they contain. Water is a basic resource not only for humans but also for these ecological systems. Spain has established that the... Continue reading "Water Resources: Key Concepts and Definitions" »

Landscape Composition

The landscape includes:

• Landforms
• Weather
• Human presence
• Flora and fauna (density and type)
• Land area
• Spectator's viewpoint
• Subjective aspects

Relief forms result from geological agents:

• Rivers: fluvial molding, wild water, pouring
• Groundwater: karst formations
• Sea waves: coastal formations
• Wind: aeolian landforms

Solar Energy Influence

Solar energy is unevenly distributed, creating:

• Atmospheric and oceanic currents
• Different climates
• Water cycle activation
• Geological agent activity
• Ecosystem functioning

Storms form where cold and hot/humid air converge.

Climate and Atmosphere

Climate determines effective geological agents and dominant weather patterns.

Meteorology studies atmospheric phenomena (precipitation, wind), represented on weather maps.... Continue reading "Landscape Elements, Weathering, and Sedimentary Rocks" »