Then from 25,000 to 10,000 years ago the lower volume Wisconsin glaciation carved many of the glacial features seen today. Burned Ridge is made of the terminal moraine (rubble dump) of the largest of these glaciers to affect the area. Today this hummocky feature is covered with trees and other vegetation. Smaller moraines from a less severe part of the Pinedale were formed just below the base of each large valley in the Teton Range by alpine glaciers. Many of these piles of glacial rubble created depressions that in modern times are filled with a series of small lakes (Leigh, String, Jenny, Bradley, Taggart, and Phelps). Jackson Lake is the largest of these and was impounded by a recessional moraine left by the last major glacier in Jackson Hole. A collection of kettles (depressions left by melted stagnant ice blocks from a retreating glacier) south of the lake is called the Potholes. The basins that hold Two Ocean Lake and Emma Matilda Lake were created during the Bull Lake glaciation. Since then humans have built a dam over Jackson Lake's outlet to increase its size for recreational purposes.