west. To the south is the Stainmore Trough. Overlying the early Palaeozoic rocks and granite are a succession of limestones, shales and mudstones dating from the Carboniferous period. At this time the part of the Earth’s crust which would later become England lay in the equatorial zone and was covered from time to time by shallow tropical seas. Repeated cycles of inundation led to the development of a series of cyclothems; the laying down of layers of limestone, shale and sandstone with occasional coal seams. Shortly afterwards, (c. 295 million years ago) molten rock once again intruded the sedimentary succession, this time resulting in the emplacement of the doleritic Whin Sill within the Carboniferous sequence. Known as whinstone locally, it baked the rocks with which it came into contact, resulting in the Sugar Limestone found in upper Teesdale. Cooling of the sill itself resulted in the formation of columnar joints, characteristic of its outcrop at places like High Cup. The sill has been dated at between 301 and 294 million years old thus straddling the Carboniferous/Permian boundary. Around the start of the Permian period, about 290 million years ago, mineral-rich waters, associated with the still warm granite, circulated within the Carboniferous succession and gave rise to mineral-rich veins which have formed the basis of a lead mining industry since at least Roman times. During the rest of this period and into the Triassic at the start of the Mesozoic era, desert sands characterised the area; these are now seen as the New Red Sandstone of the Vale of Eden, the eastern parts of which form the lower slopes of the Pennine scarp and are within the AONB. There is no bedrock of younger age to be found within the North Pennines; for much of the time since the deposition of the Triassic sandstones, it is likely the area was above sea level and subject to erosion. A series of major global climate cycles during the current Quaternary period resulted in a series of ice ages, evidence for the last ice age is found within the North Pennines both in term of erosional and depositional features. Glacial till is widespread and drumlin are encountered, both indicative of the presence of moving ice within the landscape. It may be that some higher ground was not over-ridden by ice but remained exposed through subject to harsh climatic conditions. Glacial meltwater carved channels and