In the west the Palghat and Vallagiri Hills form a connecting link between the Anamalai range and the Nilgiris, with the exception of a remarkable gap known as the Palghat Pass.
In the north is a range of primitive trap-hills known as the Cauvery chain, extending eastwards from the Nilgiris, and rising in places to a height of 4000 ft.
Its best known hills are the Nilgiris, with the summer capital of Madras, Ootacamund, 7000 ft.
At the junction of the Eastern and Western Ghats rises the bold triangular plateau of the Nilgiris, and to the south of them come the Anamalais, the Palnis, and the hills of Travancore.
These ranges are separated from the Nilgiris by a broad depression or pass known as the Palghat Gap, some 25 m.
Potatoes thrive best on the higher elevations, such as the Khasi hills, the Nilgiris, the Mysore uplands, the Shan States, and the slopes of the Himalayas; but they are also grown even in lowland districts.
The cultivation of cinchona was introduced into India in the year 1860 under the auspices of government, owing to the efforts of Sir Clements Markham, and a stock of plants was prepared and distributed to planters in the Nilgiris and in Coorg.