Landform Final

Name a mineral or rock that is more soluble than calcite or limestone

Aragonite

How are karsts classified?

dominant karst landform, drainage characteristics, nature of geologic substrate

Holokarst definition

full developed: closed depressions, little evidence of fluvial processes because drainage is underground

Fluviokarst definition

channelized surface flow present, karst landforms superimposed on fluvial landscape

Bare karst definition

bedrock exposed to atmosphere (not buried)

Mantled karst definition

limestone beneath overburden transported on top of the bedrock

Covered karst definition

limestone beneath overburden that formed in place

Subjacent karst

limestone beneath insoluble bedrock

Karst related hazards

plain flooding, reverse flooding, treacharous conditions, collapse

Process of karst carbonation

dissolving carbon dioxide gas (CO2) into a liquid, typically water, and then trapping it under pressure

Factors that influence the rate of carbonation and its effectiveness in producing karst

temperature, dilution and flushing, enhanced corrosion groundwater mixing

What is pseudokarsrt?

karst-like features that form in non-karstic rocks

Pseudokarst in CT

occurs where flow is able to wash sediments into subsurface openings. stone walls, buried wood, fill compression

What is thermokarst?

Due to melting of ice-rich ground in permafrost areas followed by subsidence

Scouring definition

due to erosion of largely insoluble rocks or sediments by rapidly flowing water

What factors influence karst development?

geological factors (like bedrock type and structure), hydrological conditions (water flow and infiltration), and environmental factors (climate and vegetation)

What are the characteristics of an epikarst region?

very permeable, Displays many dissolutional and influences hydrology, Surface water gets into the groundwater very effective in karstic areas

Vadose zone

Predominantly vertical erosion controlled by gravity rather than pressure

Phreatic zone

Flow is driven by water pressure; referred to as the “phreatic zone”

Karren definition

small-scale dissolution forms (pits, grooves, channels) that form in bare and buried epikarst zones

What are pinnacles and towers?

dissolution in epikarst creates polygonal topography (tower karst)

What are cockpits?

intense dissolution but has not yet reached a flat base

What are the main controls on doline formation?

topography/slope, lithology, water levels down and up

Where are cave entrances?

spring discharge points and dolines

What are cave passages?

cross-sectional forms reflect structural/hydrodynamic controls on cave formation

Structure controlled passages in caves

tubular, bedding plane, joints

In caves, location and density of passages is determined by…

fracture structure

Spelothelm definition

mineral deposits formed from groundwater within underground caverns

If accumulation = ablation

glacier remains stationary

If accumulation > ablation

equilibrium shifts down-ice, glaciers advance

If accumulation < abrasion

equilibrium line shifts up, glaciers retreat

Main types of glaciers

continental and alpine

What is a piedmont glacier?

fan-shaped ice mass that forms when a valley glacier spills out of a mountain

What is isostatic and eustatic sea level change?

Eu: adding or removing water, Iso: deformation by ice sheet

General location of glacier deposits in CT

along the valley floor and lower slopes, as well as in areas where the ice sheet has dammed up rivers and lakes

Plastic deformation

Due to weight/pressure of overlying ice

Basal sliding deformation

ice sheet is slightly melted on the bottom, so top heavy weight allows it to move

Pressure melting and refreezing glacial movement

High pressure causes melting, water slides to low pressure and refreezes

What is compressive flow?

decelerating ice, thickens, shears, brings sediment up from bed, entrained in ice

What is extending flow?

accelerating ice, thins and extends, brings ice down to bed

Warm based ice…

generates melt and promotes movement and sediment production

How do glaciers erode their substrate?

abrasion, plucking, meltwater sculpting

Ablation till definition

let down by melting – little/no stratification

What is lodgement till

plastered on, very dense

What is flow till?

due to melting and fluidized mass movement of till

What are the types of drift deposits associated with glaciers?

outwash plains and eskers

Difference between deltas and varves

deltas are fan-shaped ares of sediment deposit and varves are annual layers of sediment deposit

How do kettle holes form?

When a chunk of a glacier breaks off and sits in the ground, then it melts, leaving behind a depression

Where on the landscape of eastern ct do you find drift

beaches and areas where glaciers scraped away the land

why are proglacial deltas important to understanding CT's deglacial history

they serve as geological records of where and how meltwater and sediment accumulated during the retreat of the Laurentide Ice Sheet

What is stagnation zone retreat?

a type of glacier retreat where the glacier's active, flowing ice mass leaves behind a detached area of stagnant ice

Explain the morphosequence concept

time-equivalent group of landforms that extend from the collapsed ice margin to the end of the deposit

What is the source of energy that enables rivers to so effectively alter landscapes?

gradient and slope of the water

Dendritic drainage patterns

tree-like, common on uniformly resistant strata, very common

Parallel drainage patterns

uniformly resistant strata, moderately steep drainage

Trellis drainage patterns

occur in lower central valley, main channels are joined by tributaries at right angles, often occurs folded terrain or variable resistance terrain

Radial drainage patterns

outward flow from a central topographic high

Rectangular drainage pattern

perpendicular network with junctions near 90 degrees

Saturated overland flow

occurs where water table is forced back to surface to minimize infiltration

Hortonian overland flow

precipitation rate > infiltration capacity, causing runoff

Why do hydrographs have the shape that they do?

they plot volumetric rate of flow against time

What do reynolds numbers reflect

inertial forces and viscous forces

How do flow conditions change when crossing through hydraulic jumps?

flow transitions from supercritical to subcritical

What is stream discharge?

volumetric rate of flow of water flowing past a point in a given period of time

How is stream discharge calculated and what are its units?

multiplying the stream's cross-sectional area by its average water velocity. meters cubed per second

Why is it necessary to collect many point estimates of velocity from a channel?

to accurately describe its velocity because it is different in every part of the stream

How do velocity estimates relate to discharge?

The discharge of a stream is the product of its velocity

Discharge formula

Q = A x V, where Q is the discharge in cubic meters per second (m³/s), A is the cross-sectional area of the river in square meters (m²), and V is the average velocity of the water flow in meters per second (m/s)

What is a rating curve?

converting stage records to discharge

What is stage?

the water level in a river or stream, typically measured as the elevation above a reference height

What forces contribute to grain entrainment?

water flow, lift, drag, resistance