A Timeline of Earth’s Glacial Events and Climate Fluctuations
Before 1,000 Mya Faint young Sun paradox
2,400 Mya Great Oxygenation Event probably leads to Huronian glaciation perhaps covering the whole globe
650-600 Mya Later Neoproterozoic Snowball Earth or Marinoan glaciation, precursor to the Cambrian Explosion
517 Mya End-Botomian mass extinction; like the next two, little understood
502 Mya Dresbachian extinction event
485.4 ± 1.9 Mya Cambrian–Ordovician extinction event
450-440 Mya Ordovician–Silurian extinction event, in two bursts, after cooling perhaps caused by tectonic plate movement
450 Mya Andean-Saharan glaciation
360-260 Mya Karoo Ice Age
305 Mya cooler climate causes Carboniferous Rainforest Collapse
252.2 ± 0.5 Mya Permian-Triassic extinction event
199.6 Mya Triassic–Jurassic extinction event, causes as yet unclear
66 Mya, perhaps 30,000 years of volcanic activity form the Deccan Traps in India
66.0 Mya Cretaceous–Paleogene boundary and Cretaceous–Paleogene extinction event, extinction of dinosaurs
55.8 Mya Paleocene-Eocene Thermal Maximum
53.7 Mya Eocene Thermal Maximum 2
49 Mya Azolla event may have ended a long warm period
5.3-2.6 Mya Pliocene climate became cooler and drier, and seasonal, similar to modern climates.
2.5 Mya to present Quaternary glaciation, with permanent ice on the polar regions, many named stages in different parts of the world
120,000-90,000 BP Abbassia Pluvial wet in North Africa
110,000-10,000 BP Last glacial period, not to be confused with the Last Glacial Maximum or Late Glacial Maximum below
50,000-30,000 BP Mousterian Pluvial wet in North Africa
26,500-19,000–20,000 BP Last Glacial Maximum, what is often meant in popular usage by “Last Ice Age”
16,000-13,000 BC Oldest Dryas cold, begins slowly and ends sharply (B-S)
12,700 BC Antarctic Cold Reversal warmer Antarctic, sea levels rise
12,400 BC Bølling oscillation warm and wet in the North Atlantic, begins the Bølling-Allerød period (B-S)
12,400-11,500 BC (much discussed) Older Dryas cold, interrupts warm period for some centuries (B-S)
12,000-11,000 BC Allerød oscillation warm & moist (B-S)
11,400-9,500 BC Huelmo/Mascardi Cold Reversal cold in Southern Hemisphere
11,000-8,000 BC Late Glacial Maximum, or Tardiglacial (definitions vary)
10,800-9,500 BC Younger Dryas sudden cold and dry period in Northern Hemisphere (B-S)
from 10,000 Holocene glacial retreat, the present Holocene or Postglacial period begins
9,400 BC Pre-Boreal sharp rise in temperature over 50 years (B-S), precedes Boreal
8,500-6,900 BC Boreal (B-S), rising sea levels, forest replaces tundra in northern Europe
7,500-3,900 Neolithic Subpluvial in North Africa, wet
7,000-3,000 BC Holocene climatic optimum, or Atlantic in northern Europe (B-S)
6,200 BC 8.2 kiloyear event cold
5,000-4,100 BC Older Peron warm and wet, global sea levels were 2.5 to 4 meters (8 to 13 feet) higher than the twentieth-century average
3,900 BC 5.9 kiloyear event dry and cold, ends Neolithic Subpluvial in North Africa
3,200-2,900 Piora Oscillation, cold, perhaps not global. Wetter in Europe, drier elsewhere
2,200 BC 4.2 kiloyear event dry
1800-1500 BC Middle Bronze Age Cold Epoch
900-300 BC Iron Age Cold Epoch cold in North Atlantic
250 BC-400 AD Roman Warm Period
250 BC-400 AD Roman Warm Period
Climate changes of 535-536 (535-536 AD), sudden cooling and failure of harvests, perhaps caused by volcanic dust
900-1300 Medieval warm period, wet in Europe, arid in North America
Great Famine of 1315–1317
Various dates between 1250 and 1550 or later are held to mark the start of the Little ice age, ending at equally varied dates mostly after 1850, or still in progress.
1460-1550 Spörer Minimum cold
1656-1715 Maunder Minimum low sunspot activity
1790-1830 Dalton Minimum low sunspot activity, cold
Year Without a Summer (1816), caused by volcanic dust
1850-present Retreat of glaciers since 1850, Instrumental temperature record
present and recent past Global warming, perhaps to be named the Anthropocene period.
Glossary of Glacial Terms
Great Oxygenation Event – biologically induced appearance of free oxygen in Earth’s atmosphere (~2.4 Ga)
Oxygen 18 and 16 – measured in ice cores; 18 much less common; can be found in shells of a fossil T=A+B*((Ocalcite)-(Owater))
Marine Isotopic Stage 11 – interglacial period; 424,000 to 374,000 years ago; corresponds to Hoxnian Stage; concentration of CO2 similar to pre-industrial period; represents strong blooms of plankton and warm sea-temperatures overall
Stefan’s equation – (Ice accretion)=sqrt(degree days below freezing)
Aufeis – an ice form created by the successive freezings of groundwater and stream discharges. They can widen floodplains since spring flood waters have to flow around.
Basal sliding – glacier sliding over bed due to meltwater underneath
Bergschrund – a crevasse that forms between immobile sections of the ice/firm
Bering glacier – A glacier in Alaska in which nearly ⅛ of a mile went missing overnight.
Bratschen – weathering products of frost and aeolian corrasion on the calc-schists. Block like.
Cap Carbonate – layers of carbonate rocks which have been washed away due to exposure from the melting of glaciers (global warming)
Cirques glaciers are formed when the surrounding walls have ice falls or avalanches, which cause ice and snow to fall into the bowl depressions. Snow can be on the leeward slope of the mountain, where it is sheltered from wind.
Creep – AKA cold flow; tendency of a solid material to move slowly or deform permanently under the influence of mechanical stresses
Cryoconite – powdery wind-blown dust which deposits on ice
Cryogenic hummocks – cryo expulsion of clasts due to frost heaving; the rising of less dense soils and plant matters trapped within colder material (soil or ice); differential frost heave (irregular surface initially causes surface downwards freezing to spread unevenly causes the permafrost to force upwards into hummocks.
Cryoturbation – the mixing of materials due to repeated freezing and thawing (EX: cracks in roads)
Dendrochronology – the examining of tree rings as indicators of past climates
Determining glacial retreat – measure the terminus (issue is the sloping shape due to melting)
Diluvium – superficial deposits formed by flood-like operations of water
Drumlins vs Kames – Drumlins are shaped by the ice itself, rather than the meltwater, and has a regular shape. Drumlins also contain finer material such clay and shale, as opposed to sand and gravel.
Esker formation – likely to have happened from supraglacial streams flowing within the glaciers (probably during a maximum, when they were sluggish), depositing till
Fastest moving glacier – Jakobshavn glacier in Greenland; 20 m/day (35 billion tonnes)
Fellfield – contains the feldmark biome which is basically a talus slope environment (and it’s very cold and windy)
Fjard versus Fjord – fjard is an inlet that is basically a marine submerged depression/valley caused by glacial erosion, but lacks trim lines and deep troughs.
Flyggberg – larger examples of Roche Moutonnee in Sweden
Frost boil – Up Dwellings of mud due to frost heave and cryoturbation. Look like boils.
Frost heaving – the action as a result of water freezing beneath the soil, vertical movement/displacement of soil and rocks due to the freezing of water below
Gelifluction – similar to solifluction (movement of topsoil down slope) but in the presence of ice and snow.
Gelisol – A class of soil which exists in very cold climates. Has properties such as containment of permafrost within 2 meters of the soil surface.
Giant current ripples – topographic forms up to 20 m high; created by glacial lake outburst floods;
Glacier cave – most are formed by running water through the glacier; often originating at the surface and running through moulins.
Glaciolacustrine deposits – sediment deposited into lakes (ice margin lakes) which originate in rivers. These can be split into bedload and suspended deposits (first for deposition in deltas at the edges of lakes; second for deposition within the lake due to currents along the lake floor, or suspension).
Hummock – Modern: a knoll of ice above the general level of an ice field Old: lumpy terrain, often more than 2 meters above the swamps or marshes surrounding it. Causes can include decaying plant matter or unequal ice pressures.
Ice core – drill into the ice; foliations will eventually disappear along with depth due to high pressures merging the layers together (dark in summer; light in winter) (bubbles of ancient atmospheres, wind-blown dust and ash, radioactive materials); too tedious in preference to crevasse stratigraphy; usually done on top of a dome to reduce effects due to horizontal movement
Ice tongue – long and narrow sheet of ice projecting out from the coastline; forms when a valley glacier moves very rapidly out into the ocean or a lake
Ice wedge – A crack in the ground formed by a narrow or thin piece of ice that measures up to 3-4 meters in length at ground level and extends into the ground by several meters.
Icefall – a portion of some glaciers characterized by rapid flow and chaotic crevassed surface
Internal feedback – glacier melting can cause eustatic sea level rise, destabilizing ice shelves
Jokulhlaup – RELATION TO VOLCANOES; the volcanoes underneath the ice can cause meltwater formations
- Jokulhlaup driven erosion: catastrophic meltwater release tunnels away at the ground
Kame delta – glacial landform when material is deposited in a fashion similar to a kame, in front of a lake or pond (in front of the lake/pond hence delta)
Khumbu – Glacier is famous and retreated rapidly (18 m/yr)
Kryal – portion of a stream fed by meltwaters from a glacier, permafrost, or permanent ice-fields
Largest piedmont glacier in Alaska – Malaspina glacier spanning 65 kilometers in width
Ledoyom – Russian term for an intermontane depression that gets filled up with ice
Lee – sheltered from ice at point of reference; Stoss – exposed to ice at point of reference
Mass balance – difference between accumulation and ablation;
Matterhorn – A peak with 4 symmetrical faces
Misfit stream – Basically the stream that is either too large or too small to have eroded the valley in which it flows in. This is split into overfit and underfit streams (size should be pretty obvious here). If the valley is damned, you may end up with a ribbon lake.
Moraine dammed lake – The difference between this and ribbon lakes is that this is when terminal moraines block meltwater from leaving.
Nivation – process occurring under a snow patch. Mass wasting and freeze and thawing causes snow to get compacted into firn.
Penitentes – snow formations found at high altitudes; point towards the sun;
Proglacial lake – a) moraine-dammed lake b) lake trapped due to isostatic depression of the crust around the ice
Pulju moraine – moraine located in Lapland, Finland, which is known for it’s worm-like winding moraines.
Quarrying and shattering
Randkluft – headwall gap between a glacier and the headwall.
Rock basins – cylindrical depressions cut into the rock, often filled with water
Rock Drumlin – Takes on the appearance of a drumlin, until you inspect it more closely and realize it’s a drumlinoid, much closer to a whaleback.
Rogen moraine – subglacial moraine; near center of ice sheets; Lake rogen; drumlins nearby; transverse to ice flow; flues filled with water
Scablands – basically areas where the soil has been completely washed away by glacial lake outburst floods
Sorted stripes – lines of stone, vegetation, or soil which form slopes between 2o and 7o
Starvation – retreat NOT due to high temperatures, but too low precipitation
- Steady state theory: meltwater removes narrow conduit, ice sags under its own weight; POSITIVE FEEDBACK MECHANISM
Surge – fastest glacial surge: Kutiah glacier in Pakistan; 112 meters per day (average)
Taiga – Drunken trees. Caused by palsas, frost wedging/heaving, ground ice, etc.
Talik – frozen soil (see cram.com)
Theories for the formation of tunnel valleys:
Thermokarst – land surface characterised by very irregular surfaces of marshy hollows and small hummocks (much of this caused by frost heaving)
Trim line – clear line on side of valley; barren zone; marks most recent highest extent of glacier
Tunnel valley – Very large U-shaped valley; can be up to 100 km long; they are possible markers in Africa for oil exploration;
Tuya – distinct flat topped steep sided volcano that forms when lava erupts throw thick glacial ice (or ice sheet); tells about glacial ice extents and thickness; lava cools very rapidly; if penetrates, normal looking cap formed; named after Tuya butte
- Up Glacier erosion: valley head cuts the ground during deglaciation (GRADUAL)
Urstromtal – broad glacial valley formed in northern Central Europe; characterized by meltwaters flowing parallel to the ice margin.
Whalebacks – AKA rock drumlins; ice smoothed ones which lack the quarried lee side
Zungenbecken – tongue basin; basin left behind by the snout of a glacier; filled with meltwater and then surface water