Page:Provincial geographies of India (Volume 4).djvu/73

VII] The Shan States remained part of a shallow sea extending into China throughout the next period, the Jurassic, but was raised to dry land for the last time at its close. The Jurassic sea probably extended westward, covering the area now occupied by the Arakan Yoma and Naga Hills, but seems to have had no connection with a contemporaneous sea spreading at that time over the central Himalaya and Cutch.

The period which follows the Jurassic is known as the Cretaceous and precedes the Tertiary. During the Cretaceous period a widespread system of earth-movements was initiated which lasted throughout the Tertiary and does not appear to have quite ceased at the present day. The configuration of Asia was greatly affected thereby and the present system of mountains and valleys in Burma is entirely due to one of these corrugating movements. India, before these movements took place, formed part of a vast continent known as Gondwanaland which included a large part of Africa. One portion of the coast-line of this continent coincided approximately with the present east coast of India, but extended north-eastwards along the southern margin of the Shillong plateau and Mikir Hills up to the north-east corner of Assam, where it probably curved round and joined the western margin of the Shan plateau, passing southwards in a sigmoidal curve close to Moulmein and the present coast of Tenasserim and Malaysia. The sea bordering this coast was in fact an enlarged precursor of the present Bay of Bengal. At the same time another sea covered Tibet and stretched as far eastwards as Sikkim. Whether these two seas were ever connected is doubtful. The only part of Burma which formed dry land at this time, therefore, comprised Tenasserim, Karenni, the southern and northern Shan States, and the Kachin country, connected through Yunnan with the Gondwana continent of India and Africa. The Chindwin valley, the whole of the Irrawaddy valley excepting the uppermost portion, and