On the origin of the Indo-Gangetic trough, commonly called the Himalayan foredeep

1.The Question under Discussion . The plains of Northern India consist of alluvial deposits brought down by the Rivers Indus and Ganges. These plains conceal from our view a deep trough that has been formed in the solid rock of the Earth's crust. The trough is bounded on the north by mountains of the tertiary age and on the south by an ancient pre-tertiary tableland. North of the trough the Earth's crust has undergone continual compression, disturbance, and uplift since the beginning of the tertiary age; south of the trough it has remained undisturbed since the close of the palæzoic era. On fig. 1 are shown the Indo-Gangetic trough, the mountainous area in its north, and the tableland on its south. From the writings of Suess, the Indo-Gangetic trough has come to be called the Himalayan foredeep. In this paper I am proposing to consider one question only, namely, the origin of the Himalayan foredeep.