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GEOLOGY CHAPTER 9

Key Concepts:

Terms in this set (36)

Climate proxies
Climate information prior to the instrument era, developed from a variety of climate-sensitive sources, including bedrock, deep-sea and lake sediment cores, glacial ice cores, fossil pollen, coral, cave sediments and formations, soils, tree growth rings and historical documents
Paleoclimatology
The subfield of climatology that reconstructs past climates
Pleistocene Age
2,588,000 to 11,700 years ago
Holocene Epoch
11,700 years ago to the present time
Geology
The study of the lithosphere , the rocks and minerals of which it is comprised and how these features change through time
Dendroclimatology
Study of thickness and density of annual growth rings of trees for climate data
Tree-growth index
The ratio of the actual tree growth-ring width to the width expected based on the tree's age
Cross-dating
Assiduous matching of tree growth ring records from living trees with those from timbers in prehistoric dwellings, detailed tree ring chronologies are extended back in time thousands of years Study
Palmer Drought Severity Index (PDSI)
An interval of time, generally of the order or months or years, during which the actual moisture supply at a given place consistently falls short of the climatic expectation
Megadroughts
Droughts lasting at least 2 decades, and often much longer
Pollen
Tiny dost-like fertilizing component of a seed plant that is dispersed by the wind
Palynology
The study of strewn particles, including dust and other microscopic objects like spores
Isotopes
Atoms that are chemically identical, with the same number of protons but different numbers of neutrons in the nucleus
Speleothem
Calcite or aragonite (CaCO3) deposit in a limestome cave or cavern that can yield high-resolution records of past temperature and rainfall, also called DRIPSTONE. It forms when calcite precipitates from groundwater that seeped into a cave, and can either build downward from the roof of the cave creating a STALACTITE, or grow upward from the floor of the cave to form a STALAGMITE
Eutrophication
Excess nutrient input washed from the land that can stimulate the growth of algae
Paleosols
Layer of ancient soil, buried under other recent soil or sediment, and often provide clues to past climate conditions even by visual analysis
Varve
A thin layer, or lamina, of sediment deposited annually in a body of still water, usually a lake fed by a stream
Geologic time scale
A standard division of Earth history into eons, eras, periods and epochs based on large-scale geological events
Glacier
A mass of ice that flows internally under the influence of gravity
Ablation
All processes that result in a loss of glacial ice mass
Mass balance
Difference between ice mass gain (accumulation) and ice mass loss (ablation) over the course of a year, usually measured at the end of the melt season in late summer
Glacial climate
A climate favoring a positive mass balance so that new glaciers form and existing glaciers advance
Interglacial climate
A climate favoring a negative mass balance so that glaciers fail to form or existing glaciers retreat and eventually may completely waste away
Eustatic sea-level change
A worldwide fluctuation in sea level
Esker
A long steep-sided sinuous ridge composed of sediment deposited by a meltwater stream flowing through a tunnel within the ice
kame
A cone-shaped hill of sediment formed when a meltwater stream flowing on the surface of a mass of stagnant ice plunges into a crevasse
Moulin
A near vertical crevasses in a glacier
Last Glacial Maximum (LGM)
The last major glacial climatic epos that began about 27,000 years ago and reached its peak 20,000 to 18,000 years ago
Polar amplification
An increase in the magnitude of a temperature change with increasing latitude, indicating that polar areas are more sensitive to climate change
Younger Dryas
Relatively cool episode from 11,000 to 10,000 years ago, named for the polar wildflower Dryas octopetala that reappeared in portions of Europe at the time
North Atlantic Deep Water
Warm northward flowing surface water that, upon reaching the North Atlantic, cools, becomes saltier and sinks due to its increased density
D-O events
Smaller, shorter, more frequent climate "flickers" consisting of abrupt warming, almost to interglacial levels, followed by gradual cooling, also called Dansgaard-Oeschger events
Heinrich layer
Six layers of sediment deposited on the deep floor of the North Atlantic Ocean contains layers of pebbles and coats rock fragments, dating form the past 100,000 years and derived from a Heinrich event
Heinrich event
Massive discharge of icebergs from northeastern Canada (via Hudson Bay and the St. Lawrence River) during the Pleistocene Ice Age
Medieval Climate Anomaly (MCA)
period from CE 500 to 1500 of positive temperature anomalies and regional droughts, and characterized by relatively mild winters and warm dry summers in Western Europe
Little Ice Age (LIA)
A multi-century interval when the climate was more variable than the climate before the Medieval Warm Period or since, which started in CE 1300 at lower latitudes; sea-ice cover expanded, mountain glaciers advanced, the growing season became shorter, and erratic harvests caused food scarcity and considerable hardship for many people, while in Europe bitter cold winters, hot summers, drought and torrential rains punctuated decades of mild winters and warm summers
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