Glacifluvial and Glacilacustrine Landforms of the Midland Valley

Widespread meltwater erosional landforms and accumulations of glacifluvial sands and gravels have long been recognised in the Midland Valley and the adjacent upland areas. Erosional channels that record the drainage of subglacial and marginal meltwater and relate to the regional drainage of receding ice lobes, together with former ice-dammed lake spillways, are now represented by dry valleys and channels occupied by underfit streams. Depositional assemblages record the spatial and temporal evolution of glacier meltwater routeways and associated glacier karst systems in the marginal zones of the last ice sheet as it retreated from the area. These are represented by the kamiform and esker landforms created in complex and interlinked supraglacial, englacial and subglacial drainage networks and ephemeral depocentres. The glacifluvial and glacilacustrine landforms of the region are illustrated by four landsystems characteristic of general styles of glacifluvial landform-sediment production: (1) ice-sheet downwasting and marginal uncoupling in lowland terrain, exemplified by the Carstairs Kames; (2) subglacial meltwater erosion and esker sedimentation within a former palaeo-ice stream, illustrated by the subglacial meltwater channels and Alyth-Forfar esker belt of the Strathmore area; (3) ice recession into upland topography and concomitant thermal regime change, demonstrated by the lateral, sub-marginal and subglacial meltwater channels, eskers and kames formed during glacier retreat in Strathallan; and (4) ice-dammed lake formation and spillway incision, illustrated by the Ochil Hills glacilacustrine landforms and watershed overspill channels.