Common use of Synthesis Clause in Contracts

Synthesis. correlation of the Northwest and Central European Middle Pleistocene terrestrial succes- sion with the Marine Isotope Stratigraphy Chapter 6 provides a synthesis that reviews the possibilities for refinement of the low resolution Middle Pleistocene terrestrial event stratigraphy, which are sought in comparison and matching with the deep-ocean record. Although the global records are only a general guide to local climatic environment and thus a relatively poor basis for correlation, only the trends, not the amplitudes, in the oceanic isotope record are used for correlation. This trend matching is undertaken at two scales, both spatial and temporal: 1 Matching of evidence of (4th order climato-cyclic) events of global significance that are interpreted from the widespread ge- netic unconformity-bounded units, 2 Matching of palaeoclimatic evidence preserved in small-scale sequences and soil complexes in order to bridge the gaps be- tween two subsequent global-scale events. Correlations of lo- cal evidence should be done by following the post-depositional succession from a large-scale MIS-fixed basal unit or a dated level upwards. The most pronounced ð18O-maxima occurred during MIS 2, 6, 12 and 16. It is generally agreed upon that the Late Pleistocene Fen- noscandian Weichselian, British Devensian and Alpine Würmian glaciation maxima correspond to MIS 2, which in the extraglacial areas coincides with the loess accumulations in cycle B. The North Sea Eemian sea-level maximum and continental warm-stage type forest vegetation largely correspond to MIS 5e. Also the corre- spondence of the Fennoscandian Saalian and Alpine youngest Ris- sian (III) glaciation maxima, time equivalent to the Central Euro- pean loess cycle C, to MIS 6 is well accepted nowadays. Serious event-stratigraphical problems are encountered further back in the Middle Pleistocene. Conclusions on the event-stratigraphical posi- tions of the widespread glacial and subaerial sequences are: - The Fennoscandian Elsterian, British Anglian glaciation and the Central European loess cycle F occurred during MIS 12 (478- 423 ka), followed by the North Sea Holsteinian marine trans- gression (MIS 11c), - The Fennoscandian Donian glaciation and the Central European loess cycle H took place in MIS 16 (659-620 ka) which was possibly followed by a North Sea marine transgression in East Anglia. Two boundary levels of the isotopic glacial cycles, stage ▇▇▇▇▇▇- ▇▇▇▇ as defined by the SPECMAP-group (1984), are then identified for refining the chronostratigraphical position of the large-scale terrestrial events in the Middle Pleistocene. Most suitable for such chrono-correlative purposes are the deglaciation phases in the ma- ▇▇▇▇ oxygen isotope record for which the so-called terminations serve as worldwide average dates. Their time intervals coincide with particular sedimentary changes in the terrestrial sequences such as ▇▇▇▇▇’▇ ‘marklines’6 in the stacked loess sequences of Central Europe, lower bounding unconformities of coastal marine sequences in the North Sea margins and increasing tree pollen contents in (glacial) lake records. Similar to the lower boundary of the Holocene Series, formally defined at 10,000 14C BP but re- gionally dated within the deglaciation of MIS 2/1 between 18 and 6 ka BP, and of the Late Pleistocene Substage, arbitrarily defined at 128 ka (termination II) within the deglaciation phase of MIS 6/5 between 135 and 122 ka, at least two Middle Pleistocene lower boundary levels, valid for both the glaciated and non-glaciated ar- eas in Europe, can be placed at relevant MIS transitions further back in the oceanic record: 1 The lower boundary of the late Middle Pleistocene correspond- ing to the deglaciation interval of MIS 12/11 for which a date of 423 ka (termination V) has graphically been interpolated. This boundary level represents the transition of the regional Elsterian (Sanian 2/Okian) cold - to the Holsteinian (Hoxnian/ Mazovian/Likhvinian) warm Stage. Arguments for equating this transition to the boundary level at MIS12/11 are: - The dates of the Rieden phase East Eifel tephra beds at around 450-370 ka in the Middle Rhine type region, the oc- ▇▇▇▇▇▇▇▇ of pyroxene-dominated deposits in this type area and in the Anglo-Dutch North Sea type area from MIS 13 (ca. 500,000 years ago) and the stratigraphical position of the Fennoscandian Elsterian glaciation maximum in the North Sea type area intermediate of pyroxene-containing fluvial deposits (chapter 5), - The last appearance datum (LAD) of Pterocarya pollen which is tentatively used as a biostratigraphical marker in the reference pollen record of the MC Lac du Bouchet maar lake and coinciding with the North Sea Holsteinian marine trans- gression during MIS 11c (ca. 400,000 years ago), - The occurrence of exceptionally deep incision phases in sev- eral river terrace systems that probably took place during MIS 12 pre-dating the maximum ice-sheet expansion of the Fennoscandian Elsterian glaciation.