This upheaval - the consequences of which have been felt even within the historic period, by the drainage of the formerly impracticable marshes of Novgorod and at the head of the Gulf of Finland - together with the destruction of forests, contributes towards a decrease of precipitation over Russia and towards increased shallowness of her rivers.
By their means the plains of the central plateau - the very heart of Russia, whose natural outlet was the Caspian - were brought into water-communication with the Baltic, and the Volga basin was connected with the Gulf of Finland.
The Neva (40 m.) flows from Lake Ladoga into the Gulf of Finland.
The level of the Gulf of Finland at Kronstadt and of the Gulf of Bothnia at Haparanda should similarly be 15 in.
It was a populous place as early as the 11th century, and carried on a lively trade with Narva on the Gulf of Finland.
