Quaternary Geomorphology and Pleistocene Glaciation

• Quaternary geomorphology studies the landforms made, remade or left stranded by the climatic swings of the last 2.58 million years, above all the repeated growth and decay of ice sheets.
• Its central idea is that most present landscapes are palimpsests: older forms, partly erased by later processes, survive as relict (fossil) landforms that record climates unlike today’s.
• The Pleistocene glaciation is its core subject because the ice changed far more than the glaciated lands: it pressed down the crust, lowered the sea by over 120 m, rerouted rivers and moved every climatic belt.

Quaternary: Time Frame and Meaning

Quaternary, Pleistocene and Holocene

• The Quaternary Period is the youngest period of the Cenozoic Era and is still running.
  • Its base was ratified by the International Union of Geological Sciences (IUGS) in 2009 at 2.58 million years ago (Ma), at the base of the Gelasian Stage (stratotype at Monte San Nicola, Sicily).
  • The older base near 1.8 Ma was dropped because widespread Northern Hemisphere glaciation and loess deposition begin around 2.6 Ma.
• The Quaternary has two epochs.

Unit	Began	Character
Pleistocene Epoch	2.58 Ma	Repeated glacial–interglacial cycles
Holocene Epoch	11,700 years before 2000 CE (b2k)	Present interglacial; defined in a Greenland (NGRIP) ice core
Greenlandian Age	11,700 b2k	Post-glacial warming
Northgrippian Age	8,200 b2k	Begins with a short cold event
Meghalayan Age	4,200 b2k	Begins with a mega-drought; stratotype in Mawmluh Cave, Meghalaya

• The Holocene subdivisions were ratified in 2018; the Meghalayan is the only geological age defined from an Indian site.
• Key terms of the field are collected in Quaternary geomorphology and climate change terminology.

What Quaternary Geomorphology Studies

• Climate controls process, and process controls form: temperature and precipitation set the mix of weathering, mass movement and erosion in a region.
  • A change of climate therefore changes the process suite, and several climatic phases in one place leave a composite, polycyclic landscape.
  • This logic underlies climatic geomorphology and morphogenetic regions.
• Relict landforms are forms that are not in equilibrium with present climate, such as moraines in temperate farmland or dunes under grass.
  • They are the proxy data for reconstructing past landscapes (palaeogeomorphology).
  • Base-level falls and rises of the Quaternary also caused repeated rejuvenation, discussed under rejuvenation and polycyclic landforms.
• The method rests on uniformitarianism of James Hutton (1785): processes seen today operated in the past, though not always at the same rate or intensity.

Scales of Climatic Change

• Macro scale (millions of years, global): ice ages and greenhouse phases, driven by plate movements and atmospheric composition.
• Meso scale (thousands of years, regional): glacial–interglacial cycles, stadials and interstadials.
• Micro scale (centuries and less, local): Little Ice Age type fluctuations, recorded by instruments and history.
• Only long-term changes are geomorphologically decisive; short fluctuations rarely last long enough to build new landform assemblages.

Indicators of Past Climate

Geomorphological Indicators

• Diagnostic landforms: some forms are tied closely enough to one climate that their presence elsewhere signals a past climate.
  • The link is firm for glacial, periglacial and warm-desert forms; it is weaker for forms that several climates can produce.

Indicator	Past climate implied	Caveat or example
Erratics, till, moraines	Glacial	Talchir boulder beds of Odisha record a Permo-Carboniferous glaciation of India
Patterned ground, involutions, pingo scars, blockfields	Periglacial	Common in lowland Britain and Germany today
Fossil (fixed) dunes	Arid, windy	Vegetated palaeodunes of the eastern Thar
Loess sheets	Cold, dry, windy margins of ice sheets	Loess Plateau of China; Dilpur loess of Kashmir
Pluvial lake shorelines	Wetter or cooler than now	Lake Bonneville terraces, Utah; Thar playas
Duricrusts (laterite, silcrete, calcrete)	Warm, seasonally humid	Laterite in Britain and Germany is pre-Quaternary
Inselbergs and pediments	Warm, semi-arid	Often structurally controlled and polycyclic
River terraces	Changing discharge, load or base level	Himalayan and Kargil basin terraces
Raised beaches; drowned valleys	Sea-level or crustal change	Scandinavia; rias of Galicia

• Tors show the limits of diagnostic landforms.
  • David Leslie Linton (1955) explained them by deep chemical weathering and later stripping; J. Palmer and R. A. Nielson (1962) by periglacial frost action; Lester Charles King by universal pediplanation.
  • Tors from Dartmoor to peninsular India share a form but not necessarily an origin, a case of equifinality.
• Periglacial relicts beyond present permafrost limits map how far cold climates once reached; the forms themselves are covered under periglacial landforms.
• Sea-level indicators: a positive change (rise) drowns coasts; a negative change (fall) exposes them.
  • Tectonic changes are slow and local; glacio-eustatic changes are rapid and worldwide.
  • Uplifted coral terraces, such as those of the Huon Peninsula of Papua New Guinea, preserve a staircase of interglacial high stands.

Other Proxies

• Biological: pollen in lake and bog sediments, tree rings (dendrochronology), fossil faunas.
• Ice cores (Greenland, Antarctica): trapped air gives past carbon dioxide; oxygen isotopes give temperature.
• Ocean cores: the oxygen-isotope ratio (δ18O) of foraminifera tracks global ice volume and is the master Quaternary record.
• Palaeomagnetism and plate reconstructions place continents in their past latitudes, explaining tillites now found in the tropics.
• Cave deposits (speleothems): the Mawmluh Cave record of the 4.2-thousand-year drought is an Indian example.
• Historical records: freezing of the Thames, Icelandic sagas and Nile flood records cover the last few thousand years.

Ice Ages and the Pleistocene Glaciation

Ice Ages in Earth History

• An ice age is a long interval with permanent ice sheets; within it, cold glacials alternate with warm interglacials.
  • A glacial contains shorter advances (stadials) and retreats (interstadials); interstadials are colder than interglacials.
  • Karl Friedrich Schimper coined Eiszeit in 1837; Louis Agassiz made the glacial theory known through Études sur les glaciers (1840); Jean de Charpentier (1841) argued for extensive former glaciers; James Geikie (The Great Ice Age, 1874) showed multiple glaciations.

Ice age	Approximate age	Notes
Huronian	2.4–2.1 billion years	Earliest well-documented
Cryogenian	720–635 Ma	Possible “Snowball Earth”
Andean–Saharan	460–420 Ma	Late Ordovician; Sahara tillites
Late Palaeozoic (Karoo)	360–260 Ma	Gondwana ice; Talchir tillites of India
Late Cenozoic	Antarctic ice from ~34 Ma; northern ice from ~2.6 Ma	Earth is still in this ice age

• The Holocene is an interglacial within an ongoing ice age; Greenland and Antarctica remain ice-covered.

Causes of Ice Ages in Brief

• Milankovitch cycles are the accepted pacemaker.
  • Milutin Milanković (1920, 1941) linked ice ages to orbital changes in eccentricity (~100,000 years), obliquity (~41,000 years) and precession (~21,000 years), which alter summer sunlight at high northern latitudes.
  • James Hays, John Imbrie and Nicholas Shackleton (1976) found these periods in deep-sea cores, confirming the orbital control.
• Preconditions made weak orbital forcing effective in the late Cenozoic:
  • Antarctica drifting over the pole; uplift of the Himalaya and Tibet increasing weathering and drawing down carbon dioxide; closure of the Isthmus of Panama changing ocean circulation.
• Amplifiers: carbon dioxide and methane feedbacks, ice–albedo feedback and ocean circulation.
• Minor or rejected ideas: volcanic dust (effect lasts only a few years), changes in solar output (George Clarke Simpson, 1938), and pole wandering (replaced by plate movement).
• The ice-age theories as climatology are not repeated here; the geomorphic outcome is.

Extent of the Pleistocene Ice Sheets

• At the Last Glacial Maximum (LGM, about 26,000–19,000 years ago) ice covered about 25% of Earth’s land (about 8% of the whole surface), against roughly 10% of land today.
• Global mean temperature was about 6°C lower than pre-industrial.

Ice sheet	Centres	Reach and features
Laurentide	Labrador, Keewatin and Foxe domes	Up to ~3 km thick; south to ~38°N; margin close to the Missouri and Ohio rivers
Cordilleran	Coast Mountains, Rockies	Western Canada, Alaska panhandle, Washington
Fennoscandian (Scandinavian)	Scandinavian mountains, Gulf of Bothnia	Joined the British–Irish sheet; reached Germany, Poland, Russia
Alpine ice cap	Alps	Piedmont lobes into Bavaria and northern Italy
Other	Patagonia, Siberian ranges, Himalaya–Tibet	Mostly mountain and piedmont glaciers

• Beyond the ice, climatic belts shifted equatorward; the tropics were cooler, the monsoon weaker and deserts larger, while some dry basins held pluvial lakes.

Classical Glacial Stages

• Albrecht Penck and Eduard Brückner (Die Alpen im Eiszeitalter, 1901–1909) read four glaciations from Alpine river terraces; North American geologists built a matching four-fold scheme from tills.

Alpine glacial	North American glacial	Following interglacial (N. America)
Günz	Nebraskan	Aftonian
Mindel	Kansan	Yarmouth
Riss	Illinoian	Sangamon
Würm	Wisconsin	Holocene (present)

• The last glaciation (Würm in the Alps, Wisconsin in North America) spans most of the 100,000 years before the Holocene; its main advance peaked at the LGM and the ice withdrew from most of the United States by about 12,000 years ago.
• Older dates such as a Quaternary start at 1 Ma, or a Nebraskan at 300,000 years, are obsolete.

Modern View: Marine Isotope Stages

• Marine isotope stages (MIS) number the warm (odd) and cold (even) phases in the ocean δ18O record, counting back from the present (MIS 1 = Holocene).
  • MIS 2 contains the LGM; MIS 5e is the last interglacial (Eemian in Europe, Sangamon in North America).
  • The record shows dozens of glacial–interglacial cycles, not four.
• The Mid-Pleistocene Transition (about 1.2–0.8 Ma) changed the rhythm from 41,000-year cycles to larger, slower 100,000-year cycles.
• Evaluation of the four-fold scheme:
  • Each advance erases much of the evidence of earlier ones, so land records are fragmentary and undercount glaciations.
  • The Nebraskan and Kansan are now abandoned as formal units in North America; Alpine names survive only as local labels, with Donau and Biber added before Günz.
  • Correlation is now by the continuous marine and ice-core record, dated by OSL, cosmogenic nuclides and radiocarbon.

Himalayan Glaciation

• Hellmut de Terra and Thomas Thomson Paterson (1939) described four glaciations in Kashmir from moraines, terraces and the Karewa beds, matching the Alpine scheme.
• Evidence includes moraine ridges, U-shaped and hanging valleys around Gangotri and Everest, and Pleistocene terraces of the Kargil basin.
• Current view: Himalayan glaciation was not synchronous with the global LGM.
  • In the monsoon-fed ranges, glaciers often reached their maximum when monsoon snowfall was high (earlier in the last glacial cycle), while arid ranges show shrinking glaciation through time.
  • Surface-exposure and luminescence dating have replaced the Alpine correlation.

Impact of the Pleistocene Ice Age on the Crust

Glacio-isostatic Depression and Rebound

• Mechanism: an ice load presses the lithosphere into the mantle until isostatic balance is reached; the depression is roughly one-third of the ice thickness.
  • Mantle rock displaced sideways builds a low peripheral forebulge beyond the ice margin.
  • When the ice melts the depressed centre rebounds, fast at first and then slowly over tens of thousands of years; the forebulge collapses.
  • The principles are covered under isostasy and its theories.
• Fennoscandia: about 2 km of ice depressed the crust by roughly 500 m.
  • The High Coast of Sweden has risen about 285 m since the ice left about 9,600 years ago, the highest post-glacial shoreline known.
  • The Kvarken–Gulf of Bothnia area still rises at about 8–10 mm a year, and about 100 m of uplift remains.
  • Finland gains new land from the sea each year, and some harbours and shipping channels have had to be moved.
• Laurentide region: southeast Hudson Bay rises at about 10–11 mm a year, measured by GPS and satellite gravity.
  • A hinge line runs through the Great Lakes: northern shores rise, southern shores sink by 1–2 mm a year.
  • Forebulge collapse adds to relative sea-level rise along the US mid-Atlantic coast (Chesapeake Bay) and around the Netherlands and southern England.

Region	Ice load	Present vertical motion	Visible effect
Gulf of Bothnia	~2 km	Up, ~8–10 mm/yr	Raised beaches, emerging islands
Hudson Bay	~3 km	Up, ~10–11 mm/yr	Flights of raised shorelines
Scotland	Thin ice cap	Up, slow	Raised beaches
Southern England, Netherlands	Forebulge	Down, slow	Higher coastal flood risk
South of Great Lakes, Chesapeake	Forebulge	Down, ~1–2 mm/yr	Faster relative sea-level rise

• Evidence of depression and rebound:
  • Raised beaches and strandlines, often tilted because rebound was greatest near the ice centre (for example the old shorelines of Lake Iroquois).
  • Marine shells far above sea level: the Champlain Sea flooded the depressed St Lawrence lowland, and its deposits now lie well above present sea level; similar marine beds occur along the Maine coast and James Bay.
  • The Baltic passed through alternating lake and sea stages (Baltic Ice Lake, Yoldia Sea, Ancylus Lake, Littorina Sea) as rebound and sea-level rise competed at its outlets.
• Geomorphic results of rebound: base level falls relative to the land, so rivers rejuvenate and cut gorges (Quebec plateau); wave-cut benches with Pleistocene marine fossils are lifted out of reach of the sea.

Glacio-eustatic Sea-Level Change

• Water locked in ice lowered global sea level by about 120–130 m at the LGM.
  • Continental shelves became dry land; land bridges joined Asia to North America (Beringia), Britain to Europe, and Sri Lanka to India across the Palk Strait.
  • Rivers graded to the lower sea incised their valleys across the shelves and fed the heads of submarine canyons.
  • Reefs grew at lower levels on the flanks of older platforms.
• Post-glacial (Flandrian) transgression: sea level rose fast, with short meltwater pulses of several metres per century, and reached about its present level 6,000–7,000 years ago.
  • The rising sea drowned valleys and coastal lowlands, producing rias, fjords, estuaries, drowned reefs and barrier–lagoon coasts; see marine landforms.
• Reginald Aldworth Daly’s glacial control theory (1915) linked coral atolls to these sea-level swings: waves planed platforms at the lowered glacial sea level and reefs grew up on them as the sea rose.

Emergent features (land up or sea down)	Submergent features (land down or sea up)
Raised beaches, marine benches	Rias, fjords, drowned estuaries
Uplifted coral terraces	Drowned reefs and shelf terraces
Emerged strandlines around former ice centres	Submerged forests, peat and palaeochannels on shelves

Glacial Landforms of the Formerly Glaciated Lowlands

• Ice sheets scoured the shields and deposited broad till plains beyond them; the individual forms are covered under glacial landforms.
  • Parallel end-moraine belts mark successive ice-front positions across Canada, the northern United States, Germany, Poland and Sweden.
  • Drumlin fields, eskers and roches moutonnées record ice flow and meltwater routes.
  • Lake districts with disordered (deranged) drainage cover scoured shields: Finland’s tens of thousands of lakes, Vänern and Vättern in Sweden, and the Canadian Shield.
  • The Pripet (Pripyat) Marshes of Belarus and Ukraine occupy a poorly drained lowland of glacial outwash and lake deposits.
  • Mountain valleys were remodelled into U-shaped troughs, cirques, arêtes and hanging valleys; the fjord coasts of Norway were cut by ice below sea level.

Drainage Diversions and Proglacial Lakes

• Ice fronts blocked north-flowing rivers and forced meltwater along the ice margin.
  • The Missouri and Ohio follow courses set along the southern edge of the Laurentide ice.
  • The Thames was pushed south to its present valley by an earlier (Anglian) advance.
  • Proglacial lakes formed between ice and higher ground; the largest, Lake Agassiz, drained catastrophically as the ice withdrew.
• Pluvial lakes filled closed basins beyond the ice, where cooler, cloudier and sometimes wetter conditions cut evaporation.
  • Lake Bonneville (Utah) covered about 51,000 km² and exceeded 300 m in depth; about 17,500 years ago it overflowed at Red Rock Pass, releasing the Bonneville Flood down the Snake River.
  • Its shorelines (Bonneville, Provo) survive as terraces on the mountain fronts; the Great Salt Lake is a remnant.
  • Lake Lahontan occupied northwestern Nevada in the same period.

Evolution of the Great Lakes

• Before glaciation the site was a broad lowland of river valleys draining east, separated from the Mississippi basin by a low divide to the south.
• Glacial scouring deepened these valleys along weak rocks; the ice then blocked the eastern outlet, so meltwater drained south to the Mississippi.
• Isostatic depression and later tilting of the land controlled which outlet each lake used.

Stage	Lakes formed	Outlet	Approximate age
1. Ice cover	Ice over the basins; meltwater streams	South to the Mississippi	Before ~14,800 years
2. First ponding	Water trapped between moraines and the ice front	Over the divide to the Mississippi	~14,500 years
3. Lobe lakes	Chicago, Maumee, Saginaw in front of ice lobes	Illinois, Wabash and Grand rivers	~14,000 years
4. Merging lakes	Whittlesey, then Warren in the Erie–Huron basins; Finger Lakes briefly spill to the Susquehanna	Still southwest to the Mississippi	~13,000 years
5. Eastward drainage	Lundy; Iroquois in the Ontario basin	Mohawk–Hudson gap to the Atlantic	~13,000–12,000 years
6. Algonquin and Champlain Sea	Lake Algonquin over the Michigan–Huron basins; Duluth in western Superior; Champlain Sea in the St Lawrence	Trent valley, then North Bay–Ottawa outlet; Duluth via St Croix; Erie over Niagara	~11,000–9,500 years
7. Present lakes	Nipissing phase, then the modern lakes	Rebound lifts the North Bay outlet; flow returns via St Clair–Detroit to Erie, Niagara and the St Lawrence	~7,500 to ~4,000 years

• Niagara Falls began when Lake Erie first spilled over the Niagara Escarpment into the Ontario basin; it has retreated upstream ever since, cutting the Niagara Gorge.
• Rebound is still reshaping the lakes: the hinge line slowly tilts each basin, raising water against southern shores and exposing land in the north.

Post-glacial Changes and Indian Evidence

Post-glacial Climate

• Deglaciation began about 19,000 years ago and was interrupted by the Younger Dryas cold reversal (about 12,900–11,700 years ago), when ice readvanced in Scandinavia and Scotland; its end marks the Holocene.
• The Holocene Thermal Maximum (roughly 9,000–5,000 years ago) warmed the northern mid-latitudes above present, strengthened the monsoon and greened the Sahara.
  • It was first recognised in Scandinavian pollen and called the Climatic Optimum.
• The 8.2-thousand-year cold event followed the final drainage of Lake Agassiz; the 4.2-thousand-year drought opens the Meghalayan.
• Historic phases:

Phase	Approximate dates	Evidence and effects
Medieval Warm Period	950–1250 CE	Norse farms in southern Greenland
Little Ice Age	about 1450–1850 CE	Alpine glacier advance, frozen Thames, loss of Greenland settlements
Year without a summer	1816	Followed the 1815 Tambora eruption
Modern warming	since about 1850	Glacier retreat worldwide

• Many moraine-dammed lakes in the Himalaya lie behind Little Ice Age moraines abandoned by glaciers retreating since then.

Indian Evidence of Quaternary Change

• Kashmir Karewas
  • The Karewas are flat-topped fluvio-lacustrine and fluvio-glacial terraces (plateau-like benches) on the flanks of the Kashmir Valley, 1,300–1,800 m thick in total.
  • Uplift of the Pir Panjal during Himalayan mountain building ponded the ancient drainage into a large lake from about 4.4 Ma; the lake later drained when the Jhelum cut its outlet at Baramulla.
  • The succession has Lower Karewa (Hirpur Formation) lake and glacial beds, Upper Karewa (Nagum Formation) and a capping loess–palaeosol sequence (Dilpur Formation).
  • Their sediments, fossils and pollen record repeated cold–warm phases and a shift from monsoon to westerly dominance; they also hold palaeoseismic structures.
  • They carry the saffron of Pampore, but railway, highway and ring-road works and brick kilns have been excavating Karewa soil, a concern widely reported in recent years.
• Himalayan moraines and terraces
  • Nested moraines and paired terraces in Kashmir, Ladakh (Kargil), Garhwal (Gangotri) and Khumbu mark successive advances.
  • The South Lhonak Lake outburst flood (4 October 2023, Sikkim) broke a moraine-dammed lake and destroyed the Teesta III dam at Chungthang, a live hazard inherited from glacial retreat.
• Thar Desert
  • At the LGM a weak monsoon and strong winds reactivated dunes; today many are vegetated palaeodunes.
  • Lunkaransar lake rose abruptly about 6,300 radiocarbon years ago and dried by about 4,800 radiocarbon years ago; Sambhar and Didwana playas carry similar lake-level records.
  • Palaeochannels: the Sutlej abandoned the Ghaggar–Hakra channel between about 15,000 and 8,000 years ago, long before the Harappans settled along the dry valley.
• Coasts and shelf
  • On the east coast the sea stood about 100 m lower near 14,800 years ago, rose in rapid pulses, and stood a few metres above present in the mid-Holocene, leaving inland palaeo-deltas and beach ridges.
  • On the western shelf, submerged terraces at about 92, 85, 75 and 55 m, including oolitic limestone of the “Fifty Fathom Flat” dated to about 9,200 years, mark pauses in the rise.
  • Offshore Dwarka, the Archaeological Survey of India’s Underwater Archaeology Wing resumed surveys in February 2025; submerged structures there are studied for late-Holocene shoreline change.
• Gondwana tillites (Talchir, Odisha) show that India lay under ice in the Late Palaeozoic, long before the Quaternary.

Current Relevance and Evaluation

Ongoing Adjustment and Monitoring

• Glacio-isostatic adjustment continues: Hudson Bay and the Gulf of Bothnia are still rising, and forebulge areas are still sinking.
• Satellite gravimetry (GRACE, 2002–2017, and GRACE Follow-On since 2018) sees the mass returning under Canada and Scandinavia.
  • This signal must be removed before GRACE data can measure present ice loss in Antarctica and Greenland or groundwater loss in north India.
• NISAR, the ISRO–NASA radar satellite launched on 30 July 2025, maps ground deformation, glaciers and ice sheets several times a month.
• Present warming reverses the Pleistocene story:
  • 2024 was about 1.55°C above pre-industrial; global sea level rose 4.7 mm a year over 2015–2024, double the rate of 1993–2002, and 2022–2024 saw the most negative three-year glacier mass balance on record.
  • Melting ice sheets will cause new rebound under Greenland and West Antarctica, while coasts on old forebulges sink.
  • Human emissions may postpone the next glaciation by tens of thousands of years.
• Anthropocene: a proposal to end the Holocene in the 1950s (Crawford Lake, Canada, as the marker) was rejected by the IUGS in March 2024; the Holocene remains the formal epoch, and the Anthropocene stays an informal term.

Critical Evaluation

• Strengths: relict landforms, shorelines and sediments give a spatial record that cores cannot; rebound and sea-level data fix mantle viscosity and ice volumes.
• Limits:
  • Land records are fragmentary, as later ice and erosion erase earlier evidence; hence the four-glacial scheme undercounted glaciations.
  • Equifinality: similar forms (tors, pediments, duricrusts) arise under different climates or from structure.
  • Asynchrony: glaciers respond to local snowfall as well as temperature, so mountain and monsoon regions do not follow the ice-sheet chronology.
• Current approach: landforms dated by OSL, cosmogenic nuclides and radiocarbon, and tied to the marine isotope and ice-core timescale, with glacio-isostatic models linking ice, crust and sea level.