chapter 11

Fracking (Hydraulic Fracturing): A controversial technique for extracting natural gas from shale, which is deeply buried sedimentary rock.
Proponents argue that fracking is a cost-effective method to access vast U.S. natural gas reserves.
Opponents highlight potential environmental risks, such as:
- Groundwater contamination.
- Inducing earthquakes (e.g., notable quakes in 2016 in Oklahoma).

Definition: Natural gas trapped within shale, which is fine-grained sedimentary rock formed from ancient mud.
Formation: Shale contains organic matter that can decompose into oil and gas under specific conditions.
Key Production Area: The Marcellus Shale, stretching from Ohio to western New York, is considered one of the world's significant gas reservoirs, covering 60% of Pennsylvania with around 6000 wells.
Methane: The primary component of natural gas, also a potent greenhouse gas, making the U.S. natural gas industry a significant contributor to methane emissions.

Breaking the Rock: Release of methane by fracturing rocks to allow gas to escape into cracks and rise.
Horizontal Drilling: A standard well design that descends 2.4 km (1.5 mi) down, then extends horizontally. This technique:
- Exposes a larger rock area for gas extraction.
- Enhances prosperity by maximizing fractures.
Fracking Fluid Composition: A mix of:
- Water
- Sand or glass beads (to keep fractures open)
- Chemical additives (undisclosed, some of which may be toxic).

Land Disturbance: Changes landscapes and generates hazardous by-products.
Water Usage: Massive water requirements potentially deplete local resources, adversely affecting ecosystems.
Wastewater: Generated toxic wastewater linked to increased earthquake activity through injection wells.
Air Pollution: Methane contributes to greenhouse gas accumulation, exacerbating climate change.

Growth Period: The fracking boom began in 2007, primarily in Pennsylvania, North Dakota, Colorado, Oklahoma, and Texas.
Projections: U.S. shale gas production anticipated to surpass 50% of overall natural gas production by 2040.
Market Fluctuation: In 2015, falling oil prices led to a downturn in shale gas production, casting uncertainty on its future viability.

Endogenic System: Internal Earth processes driven by heat that create mountains and cause volcanic eruptions.
Exogenic System: External forces that shape Earth's surface through weathering and erosion.

Geology: The science of Earth’s history, composition, structures, and processes.
Geomorphology: A subfield studying landform origins, evolution, and distribution.

Definition: A term used to describe the modern era characterized by significant human impact on Earth’s geology and ecosystems.
Significant Changes: Deforestation, agriculture, climate change, and mining reflect the Anthropocene's lasting changes.

Structure: Chronological summary of Earth's history over 4.6 billion years categorized into eons, eras, periods, and epochs.
Key Events: Six major extinction events shaped life on Earth, with current climate alterations due to human activities marking an ongoing extinction event.

Relative Age vs. Numerical Age: Geologists utilize both frameworks for dating events or features based on sequence (relative) or exact years (numerical).
Current Epoch: We live in the Anthropocene, indicating significant human influence on Earth.

Layers: Earth consists of the core, mantle, and crust, each with distinct properties and temperature gradients influencing geologic processes.
Seismic Evidence: Knowledge of Earth’s internal structure primarily from indirect evidence like seismic waves generated during earthquakes.

Igneous Rocks: Formed from the cooling and solidification of magma (intrusive) or lava (extrusive).
Sedimentary Rocks: Result from the accumulation of sediments compacted and cemented together.
Metamorphic Rocks: Created through the alteration of existing rocks under heat and pressure.

Ongoing Change: Geological and climatic changes continually reshape both Earth's crust and surface landscapes.
Human Impact: Addressing the anthropogenic alterations to the environment and their implications for sustainability.