declivitous

But I plodded on and on, finding all things looking beautiful in that autumn glow, until at last I found myself descending the declivitous road into Wretchedville and to destruction.

From Humorous Readings and Recitations In prose and verse by Various

Its chasms resemble the declivitous shores of the sea; the wind often fills them with snow; the paths are almost impracticable, the descent is so rapid and slippery.” 

From Travels in Tartary, Thibet, and China During the years 1844-5-6 Volume 2 by Évariste Régis Huc

High declivitous, masses of rock formed a sort of immense cairn.

From Dave Dashaway and His Hydroplane by Roy Rockwood

Everywhere on the declivitous waysides, tow-haired, blue-eyed children guarded herds of goats, as their forbears had done in the days of Vercingetorix, the Gaul.

From The Mountebank by William John Locke

But four miles inland the bed becomes rugged and declivitous, and the mountain walls close in, forming a most magnificent cañon from 1,000 to 2,500 feet deep. 

From The Hawaiian Archipelago by Isabella L. (Isabella Lucy) Bird