Quiz 3 (Continued) Flashcards
Mineral
Naturally occurring crystalline solid.
Rock
An aggregate of one or more minerals.
Lava
Magma (molten material) on earth’s surface
Where do pyroclastic rocks/tuff/ash form?
Where magma explodes violently into atmosphere and falls back to ground
Felsic composition vs Mafic composition?
Felsic: Lighter in color
Mafic: Darker in color
Extrusive vs. intrusive?
Extrusive: Volcanic. Aphanitic texture (small crystals, glassy, rapid cooling)
Intrusive: plutonic. Phaneritic texture (large crystals due to slow cooling)
What type of rock do we see most?
Sedimentary (75%) they’re at the top
Igneous (25%) in bedrock (mostly)
Compaction
Tighter packing of sedimentary grains causing weak lithification and a decrease in void space (holes), usually from weight of overlying sediment
Cementation
Process by which clastic sediment is lithified by precipitation of mineral cement, such as calcite cement, among the grains of the sediment
Pathways common with sedimentary rocks
Erosion
Deposition
Compaction
Cementation
Lithification
Classic sedimentary rocks
Composed of minerals and rock fragments that are:
- incompletely weathered or I weathered (immature sediments) - relatively stable with respect to weathering (mature sediments)
Classified based on:
- clast size (clay-silt-sand-pebble) and shape (roundness) - mineral and/or lithic clast type
Types of channels?
Straight
Meandering
Braided
Sheetflow (overland flow)?
Surface water that flows unconfined over the land
Stream/river
Flowing water confined to a channel
Runoff?
Movement of land water to oceans
Sheetflow and streamflow together.
A small, medium, and large river move at same flow rate. Which one have highest discharge?
Biggest one.
Bar
An elevated region of sediment (such as sand or gravel) that has been deposited by the flow.
How fast can rivers change shape?
Many times throughout one person’s life. Doesn’t take millions of years.
Sources of energy for hydrologic cycle?
Sun
Gravity
Sublimation
Freezing
Melting
Solid to gas
Liquid to solid
Solid to liquid
What are the effects of climate change?
Change in precipitation
Influences plants and animals that live in freshwater lakes and rivers, altering their habitat and possibly bringing life-threatening stress and disease
Challenges for flood control and river
What can we do about floods?
1) engineering approach to control flooding
2) regulatory approach designed to decrease vulnerability to flooding
3) preparedness by predicting and forecasting flood times and locations
4) education of the public
Flood watch
High flow or overflow of water from river is possible in given time period.
Can apply to heavy runoff or drainage of water into low-lying areas
Generally issued for flooding that’s expected to occur at least 6 hours after heavy rains have ended
Don’t have to leave but get prepared
Flood warning
Occurring or is imminent in warning area
Flash flood watch
Flash flooding is possible in or close to watch area
Generally issued for flooding that’s expected to occur within 6 hours after heavy rains ended
Flash flood warning
Is actually occur in or is imminent in warning area
Can be issued as result of torrential rains, fam failure, or ice jam
Coastal flood watch
Possibility exists for the inundation of land areas along coast within next 12-36 hours
Coastal flood warning
Land areas along coast are expected to become, or are, inundated by water above typical tide action
Channelization advantages and disadvantages
A: make stream more suitable for navigation
Restrict water to certain area of stream’s natural bottom lands so bulk of such lands can be made available for agriculture
Flood control
D: loss of wetlands
Straightening causes streams to flow more rapidly, which can cause increase in soil erosion
Can also increase flooding downstream from channelized area with net effect
Type of weather pattern associated with heavy rain in Vegas
Warm humid air meets cool air
