Las Vegas Physical Geography Quiz
Basin & Range landforms, dry washes (10 questions).
Las Vegas Physical Geography Quiz: Quick Study Notes
The physical geography of Las Vegas is largely defined by its location within the vast Basin and Range Province. This unique geological setting, combined with an arid desert climate, shapes the distinctive landforms and hydrological features, such as dry washes, that are characteristic of the region. Understanding these elements is key to comprehending the local environment and its challenges.
Characterized by alternating narrow, fault-block mountain ranges (horsts) and broad, flat valleys (grabens). Las Vegas sits in one such graben.
Ephemeral stream beds that are typically dry but can quickly fill with torrents of water during sudden, intense desert thunderstorms, leading to flash floods.
Fan-shaped deposits of sediment at the base of mountains, formed by dry washes depositing debris as water exits canyons and loses energy.
Las Vegas experiences extreme dryness with very little annual rainfall. When rain does occur, it’s often heavy and localized, contributing to dry wash activity.
Key Takeaways on Las Vegas Physical Geography
- The Las Vegas Valley is a graben, a down-dropped block of land, within the larger Basin and Range Province.
- Surrounding mountains like the Spring Mountains are horsts, uplifted blocks of land.
- Dry washes are a critical part of the desert hydrology, channeling infrequent but powerful storm runoff.
- Alluvial fans are prominent landforms formed by the deposition of sediment carried by dry washes from the mountains.
- Flash floods are a significant natural hazard in dry washes due to the impermeable desert soil and intense rainfall.
- The region’s arid climate dictates the ephemeral nature of surface water features, including dry washes.
Frequently Asked Questions
What defines the Basin and Range Province around Las Vegas?
The Basin and Range Province is characterized by a series of north-south trending mountain ranges (horsts) separated by broad, flat valleys (grabens), formed by tectonic extension and faulting over millions of years. The Las Vegas Valley is one such graben.
Why are dry washes important in Las Vegas?
Dry washes are essential natural drainage channels in arid environments. They manage storm runoff, transport sediment from the mountains to the valleys, and are key indicators of the region’s infrequent but intense rainfall patterns. However, they also pose flash flood risks.
What is an alluvial fan, and how does it relate to Las Vegas?
An alluvial fan is a cone-shaped deposit of sediment formed where a canyon opens onto a flatter plain. In Las Vegas, alluvial fans are prominent features at the base of the surrounding mountains, created by dry washes depositing sand, gravel, and rock as floodwaters lose energy.
What causes flash floods in dry washes in the Las Vegas area?
Flash floods are caused by intense, short-duration rainfall events over desert terrain. The arid soil has low permeability, leading to rapid runoff that quickly fills dry washes, turning them into fast-moving, dangerous rivers.
How does the geology of Las Vegas affect urban development?
The Basin and Range geology impacts development by dictating suitable building areas (valleys vs. steep mountain slopes), influencing groundwater availability, and requiring careful planning for flood control due to dry washes and alluvial fans.
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