Next he introduced us to the rocks which underlie our part of the Maun valley. Terminology has changed over the years, so we agreed to use the traditional names applied to the rock layers. The Bunter Sandstone (also known as \u2018Nottingham Castle Sandstone\u2019) is youngest and nearer the surface, whereas Lower Mottled Sandstone (also known as \u2018Lenton Sandstone\u2019) is older and lower down. It is also softer and more easily eroded. We were also introduced to \u2018Marl\u2019 which is clay rock rich in lime. Importantly, Marl does not allow water to pass through. This means that any water in the sandstone that is between two layers of Marl will be trapped unless it finds a way out.<\/p>\n Stephen showed us photographs he took in Mansfield of different geological layers:<\/p>\n This portion of the presentation was followed by a group discussion about influences on the landscape at Spa Ponds. Such influences included:<\/p>\n Arising from the discussion, Stephen explained how water flowed over the surface and sometimes through the rocks and soil. The interrelationship between the sandstone layers which are permeable (allow water through) and the scattered marl beds which are impermeable (don\u2019t allow water through) is the likely cause of the springs which feed Spa Ponds.<\/p>\n Discussions moved on to include ideas for mapping of springs and ponds in the vicinity of Spa Ponds to help us understand the setting. Also discussed was measuring the time it takes between weather events, e.g. rainfall, and observable changes to the water flow between the ponds and\/or the water level in the ponds\/river.<\/p>\n Next Stephen treated us to an explanation of the impacts of the Anglian and Devensian Ice Ages in this area. He noted how one effect of glaciation was that the River Trent was diverted because of melting glaciers. This is relevant to Spa Ponds as the River Maun flows towards the Trent. It is safe to assume that the area we know of as Spa Ponds would have been completly covered by ice during the earlier Anglian Ice Age because Anglian deposits are found nearby. However, this area would have been on the edge of the ice sheets during the Devensian Ice Age. The valley that includes Spa Ponds could have been formed in the interglacial (warm) period between the Anglian and Devensian Ice Ages.<\/p>\n The Anglian and Devensian periods are the geological terms for what archaeologists call the stone age. It is likely that there were people in this landscape. At Farndon (in the Trent Valley) the \u2018Ice Age Journeys\u2019<\/a> project has been investigating stone age hunting camps, so it is possible that the hunters also passed along the Maun valley.<\/p>\n Stephen introduced us to the term \u2018periglacial\u2019 (meaning \u2018on the margins of a glacier\u2019), explaining how Spa Ponds would have been part of an environment that was on the edge of a glacial environment, meaning that water on the land would freeze and then thaw repeatedly to cause weathering. In summer, meltwater would flow across the frozen subsoil (permafrost) just as it does in Siberia today. Seasonal streams charged with meltwater flowing over the frozen ground could have created valleys which now have no surface streams, (and are known as \u2018dry\u2019 valleys). This proposition is supported by the LiDAR evidence of \u2018side valleys\u2019 and what Stephen described as the Dendritic drainage pattern (see photo above).<\/p>\n Alternatively, Stephen explained how limestone is eroded into caves by underground water and how in some areas along the Maun such caves have collapsed to create valleys.<\/p>\n Stephen then offered us a series of questions to help us focus on what we know and what we might wish to know about the Spa Ponds landscape. He also posed the following three important questions to help us decide our next steps:<\/p>\n![\"Diagram](\"https:\/\/foresttown.net\/wp-content\/uploads\/2017\/06\/SPHP-Geology-Slide-2.png\")
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