The River Lee The River Lee is also part of Cork’s geological heritage. Rivers create rocks, but they are also created from rocks. This is especially true here in Cork. Rivers transport sediments which accumulate, solidify and eventually turn into layers of rocks. On the other hand, underlying geological structures and features will influence the path of a river. The water of the Lee flows 100 kilometres from the lake at Gougane Barra to Roches Point in a near east-west alignment. Its east-west alignment is not arbitrary but follows the folds and faults that were formed during the continental collisions of the Variscan orogeny. The same with the Lee’s tributaries (small rivers leading to one bigger river), though these smaller rivers follow a north-south trend instead. And as you might suspect, this trend is also caused by the underlying geology. The north-south alignment of the tributaries follows smaller faults that were formed at a 90-degree angle to the main folding and faulting that happened when the rocks of Cork were squeezed and deformed. The faults act as weaknesses in the rocks that water then flows through.
Over long periods of time these streams cut into the rock, eroding more rock material away and eventually forming river valleys. This pattern is visible over the course of the Glashaboy River running through Glanmire, and the River Shournagh entering the Lee near Kerry Pike. Both of these rivers flow into the Lee where large faults exist in the rocks underneath them. A CROPPED GEOLOGICAL MAP OF CORK n Dark blue: Main rivers n Black lines: Large faults n Red/orange: Old Red Sandstone n Yellow: Carboniferous sandstones, siltstones and mudstone n Light blues: Carboniferous limestones n Pink: Cork Red Marble
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