The Oak Ridges Moraine is an ecologically important geological landform in the Mixedwood Plains of south-central Ontario, Canada. The moraine covers a geographic area of 1,900 square kilometres (730 sq mi) between Caledon and Rice Lake, near Peterborough. One of the most significant landforms in southern Ontario, the moraine gets its name from the rolling hills and river valleys extending 160 km (99 mi) east from the Niagara Escarpment to Rice Lake, formed 12,000 years ago by advancing and retreating glaciers (see geological origins, below) during the last glaciation period. Below the approximately 200 metre thick glacial derived sediments of the moraine lies thick bedrock successions of Precambrian rocks and up to 200 metres of Ordovician aged rock (see geology below), capped by a regional unconformity of erosion and non-deposition to the Quaternary period. Rivers and lakes scatter the landscape and are important for creating habitat for the rich diversity of species of animals, trees and shrubbery (see ecology). These are also the supply of fresh water to aquifers in the moraine through complex subterranean connections (see hydrology). Construction development nearby, and with expansion of communities around the moraine in need of potable water, it is a contested site in Ontario, since it stands in the path of major urban development (see political action). Conservation of the moraine is thus an important step for keeping aquifers in a safe drinkable condition while also protecting the natural ecosystems surrounding and within the moraine (see conservation). This region has been subject to multiple decades of scientific research to study the origins of formation, and how early communities used the land. A larger focus currently is how to source potable water without removing the aquifer entirely (see research section).