<P> During the Upper Cretaceous, about 70 million years ago, the north - moving Indo - Australian plate (which has subsequently broken into the Indian Plate and the Australian plate) was moving at about 15 cm per year . About 50 million years ago this fast moving Indo - Australian plate had completely closed the Tethys Ocean, the existence of which has been determined by sedimentary rocks settled on the ocean floor and the volcanoes that fringed its edges . Since both plates were composed of low density continental crust, they were thrust faulted and folded into mountain ranges rather than subducting into the mantle along an oceanic trench . An often - cited fact used to illustrate this process is that the summit of Mount Everest is made of marine limestone from this ancient ocean . </P> <P> Today, the Indian plate continues to be driven horizontally at the Tibetan Plateau, which forces the plateau to continue to move upwards . The Indian plate is still moving at 67 mm per year, and over the next 10 million years it will travel about 1,500 km into Asia . About 20 mm per year of the India - Asia convergence is absorbed by thrusting along the Himalaya southern front . This leads to the Himalayas rising by about 5 mm per year, making them geologically active . The movement of the Indian plate into the Asian plate also makes this region seismically active, leading to earthquakes from time to time . </P> <P> During the last ice age, there was a connected ice stream of glaciers between Kangchenjunga in the east and Nanga Parbat in the west . In the west, the glaciers joined with the ice stream network in the Karakoram, and in the north, they joined with the former Tibetan inland ice . To the south, outflow glaciers came to an end below an elevation of 1,000--2,000 metres (3,300--6,600 ft). While the current valley glaciers of the Himalaya reach at most 20 to 32 kilometres (12 to 20 mi) in length, several of the main valley glaciers were 60 to 112 kilometres (37 to 70 mi) long during the ice age . The glacier snowline (the altitude where accumulation and ablation of a glacier are balanced) was about 1,400--1,660 metres (4,590--5,450 ft) lower than it is today . Thus, the climate was at least 7.0 to 8.3 ° C (12.6 to 14.9 ° F) colder than it is today . </P> <P> Despite their scale the Himalayas do not form a major watershed, and a number of rivers cut through the range, particularly in the eastern part of the range . As a result, the main ridge of the Himalayas is not clearly defined, and mountain passes are not as significant for traversing the range as with other mountain ranges . The rivers of the Himalayas drain into two large river systems: </P>

Most of the fresh water lakes are located in the himalayan region. explain