The Moreton-in-Marsh terminal moraine

 

Two phases of glaciation, both during the Wolstonian, as identified by the research team.  In the early stadial it is proposed that there was a shoreline associated with Glacial Lake Harrison just to the north of Moreton-in-March, with an ice edge near Gloucester marking the greatest extent of the Wolstonian Severn Glacier. Then in the late stadial ice filled the Lake Harrison basin, almost reaching Moreton-in-Marsh and leaving behind a distinct terminal moraine and a spread of glaciofluvial sands and gravels.

I have been intrigued for some time by the glacial features around the Jurassic escarpment and the Cotswold Hills, and especially by the sediments near Moreton-in-Marsh.  This new paper takes a fresh look at the evidence, and comes up with some interesting conclusions.

https://royalsocietypublishing.org/doi/10.1098/rsos.220312

Appendix A. The Moreton Stadial Event

As noted in the main text, a glacial moraine forms rising ground (145–137 m OD) around the village of Moreton-in-Marsh, Warwickshire (SP 205 323) (figures 1 and 14b). This moraine complex marks the known maximum extent of glaciation during the Late Wolstonian Substage within the English West Midlands. 

The Moreton moraine ‘drift’ deposit was first mapped by Dines [168] and identified/interpreted by Tomlinson [16]. Bishop [13] subsequently linked the deposits as the maximum southern extension of the glacial sediments which form the Wolston Glacigenic Formation of the Wolstonian Stage [1,6,11]. The Moreton moraine ‘drift’ occurs as a series of ridges for ca 30 km2 around Moreton-in-Marsh and south to Broadwell (figure 14b). The glaciogenic deposits were proven in a borehole to a depth of 21 m [134]. North, at Stretton-on-Fosse (SP 218382) (figure 1 and table 1, 11), Bishop [13] described a series of deposits, exposed locally, where a diamicton unit was correlated with the Oadby Till Member, which locally overlies the Moreton Till Member of Tomlinson [16] and Sumbler [134]. 

In the Moreton-in-Marsh area, two glacial diamicton units are recorded interdigitating with and including the local Paxford Gravel Member [16,134,168]. The stratigraphically lower, Moreton Till of the Wolston Glacigenic Formation, local to Moreton-in-Marsh, was described by Bishop [13] as a locally laminated diamicton deposited at the margin of the pro-glacial Lake Harrison. It is equivalent to the Thrussington Till Member of the Wolston Glacigenic Formation. This diamicton unit, is directly overlain by the regional Oadby Member of the Wolston Glacigenic Formation. At Stretton-on-Fosse, faulting of the upper diamicton was reported, suggesting interpretation of the landform complex as a push moraine complex [13,134]. As discussed above, the pro-glacial Lake Harrison existed through two phases. Meltwaters from the second phase incised a channel down to 128 m OD through the confining Moreton moraine ridge, forming the Moreton Gap. This channel is critical to the regional stratigraphical correlation with the Upper Thames valley fluvial sequence during the Late Wolstonian Substage. 

The Moreton moraine landform complex is representative of the maximum extent of regional glacial deposition (Thrussington Till and Oadby Till members) of the Wolston Glacigenic Formation [1,6,11,13,134]. Its significance in marking the Wolstonian Stage glacial maximum limits, which have been dated herein to the Late Wolstonian Substage, give the Moreton moraine regional importance. Since it represents the glacial maximum extent, the Moreton moraine-ridge complex, and its associated exposure at Stretton-on-Fosse (table 11), are therefore proposed here as the climatostratigraphic stratotype of the Moreton Stadial, the first of two stadials (the latter being that of the Pershore Stadial in Gibson [68]) that can be identified in central Britain in the Late Wolstonian Substage.

Just a reminder of where this all sits in the glacial sequence of the UK:

MIS2 is the Late Devensian or LGM, MIS6 is the Late Wolstonian, and MIS8 is the Early Wolstonian.  there is some confusion about MIS7 -- was there really an interglacial between those two very cold (glacial) phases?  Watch this space....