About 185,000 years ago, a side lobe of the Walensee/Reinglacier overlapped on the threshold at the present
Pfannenstiel eastern slope from
Hombrechtikon into the
Glatttal towards Niederweningen, and eroded the overdeepened rock rut of the present Wehntal area. During melting of the glacier, Wehntal, the lower
Glatttal and Furttal filled about 180,000 to 150,000 years ago with cold glacial lakes. After another glacier maximum about 140,000 years ago, the ice melted in the last
Eemian (interglacial) period back far into the alpine valleys, and great lakes with border union fens filled the former glacial basin. During the
Würm glaciation and again about 45,000 years ago, mammoths and other Ice Age animals lived in the largely silted Wehntal. During the last glacial maximum about 24,000 years ago the glaciers pushed again to the lower Glatttal, but not to Wehntal. With the increasing warming period about 20,000 years ago, the glaciers melted away in stages to Zürich, later
Hurden and formed the
Seedamm at the
Obersee lake shore respectively the
Ufenau,
Lützelau and
Heilig Hüsli islands on
Zürichsee, and finally the glaciers retreated into the alpine mountains. In 1890 the most important site of ice animals in Switzerland was discovered in
Niederweningen. Particularly the uppermost deposits with the so-called
Mammut turf layer were studied up in about depth, and between 1983 and 1985 by three research boreholes to a depth of . In 1994 a groundwater bore in
Oberweningen proved that the Wehntal area originally laid at least deeper than the present valley floor and had to be caused by glacial erosion. In 2003 the remains of a
Mammoth were found, and further finds resulted in the establishment of the present
Mammutmuseum Niederweningen. The heartland of the possessions of the medieval
House of Regensberg was in the
Furt and Wehn valleys besides the Lägern chain, where around 1050 AD the family built its ancestral seat
Altburg near
Zürich-Affoltern and two centuries later
Neu-Regensberg on the eastern Lägern slope. == Transportation ==