Origin of thalweg. German Talweg, Thalweg : Tal, Thal, valley (from Middle High German tal, from Old High German) + Weg, way (from Middle High German wec, weg, from Old High German weg; see wegh- in Indo-European roots).
Besides as Sandra said the natural age of weaning is older than 2 and the WHO advises breastfeeding for a minimum of 2 years. It is not ridiculous that your son wants milk at 22 months. I fed my oldest child until 2.5 and am still feeding my 18 month old and plan to keep going as long as I can.
Stop Breast Feeding Your Baby: How to Begin Weaning your Nursing Baby off Breast Milk to Dry Up Lactation & Avoid Engorgement. How to Stop Lactation Avoiding EngorgementIf you want to stop breastfeeding and are wondering how to dry up your milk supply, take heart.