Lecture 22: Quaternary Interglacials - Analogues? Flashcards
Which milankovitch cycle has dominated the glacial-interglacial cycles throughout most of the quaternary?
Obliquity
What milankovitch cycle has started to dominate the quaternary period in the most recent 1 million years?
Eccentricity
What has the transition from the obliquity to the eccentricity cycle meant for the occurrence of glacial and interglacial periods?
The glacial-interglacial cycle has become much more pronounced and clear
What are the names for the last interglacial?
Ipswichian and Eemian
What MIS is the last interglacial?
MIS 5
How many sub stages are there within MIS 5?
5
Which sub stage within MIS 5 is most closely studied for information about the last interglacial and why?
MIS 5e because it is the period when the last interglacial was most intense
Who was James Geikie?
Scottish geologist
What did James Geikie’s 1872 book consist of?
the organic deposits and Palaeolithic remains which he found in glacial tills and moraines he believed could not have occurred after tha last glacial period because there were glacial deposits on top indicating that another glacial period occurred after. Instead he claimed that this must have occurred before in a period which he called an interglacial
Who was Pieter Harting?
Dutch biologist in the late 19th century
What did Pieter Harting study and where?
Boreholes near Amersfoort in Netherlands
What did Pieter Harting find in the boreholes and what did he believe they were an indication of?
Marine sediments and shells of Mediterranean species which he believed were an indication of a previously warmer climate with higher sea levels
What did Pieter Harting name the period which he observed from boreholes? what would this later become?
Systeme Eemien - this would later become the widely recognised name for the last interglacial
Why does evidence for the last interglacial within Britain not come from peat and lake cores?
Because they normally do not stretch back far enough
What type of record does evidence from the last interglacial within Britain come from?
Archaeological and sediment record
What sort of site was analysed for the archaeological record?
Coastal/inland caves
What sort of evidence came from the sediment record in Britain?
River terraces and raised beaches
Where part of Britain does evidence for the last interglacial come from? why?
Southern parts because records further north were destroyed during last glacial maximum
What are some of the most famous sites for evidence for the last interglacial within Britain?
Bobbitshole (near Ipswich), Trafalgar square, Joint Mitnor Cave
How do river terraces provide evidence of the geological past?
In glacial and interglacial periods, river respond in certain ways that can either result in incision or aggradation. The deposits from that period can then be analysed and use the law of superposition, to reconstruct different periods
How do raised beaches and their deposits provide evidence of the geological past?
The deposits can be used to determine what sea level was at the time by dating the sediments. The sea level is a good indication of whether it is an interglacial or glacial period
What rivers contain evidence of previous river terraces?
Thames and Orwell
What areas contain evidence of previous raised beaches?
Saunton and Westward Ho!, Portland Bill, Hope’s Nose
How do caves contain evidence of geological past?
They contain evidence of many fauna such as hippopotamus, elephants and wild boars
What are some areas which contain caves which are used to analyse the past?
Joint Mitnor, Tornewton and Victoria Cave
Describe the Bobbits Hole UK type site? (type of record, depth, characteristics)
Organic rich mud that is 3.5m deep and banded by river terrace deposits from MIS 4 and MIS 6 above and below this mud layer