The phrase 'the base of which' is correct and usable in written English.
You can use this phrase when you are referring to the basis or foundation of something. For example, "The study highlights the importance of a holistic approach, the base of which is the reduction of poverty."
The salad was leaves of lettuce with a chopped-up arrangement, the base of which was wholewheat".
The oak tree at the base of which they are said to have perished was struck by lightning in 1879.
She said it then climbed a tree, at the base of which officers found four boxes of stolen crockery.
Ruys's innovation was to develop a doughnut-shaped waxed-paper cocoon, the base of which is buried underground.
First the mixed odors of the ferries, the base of which is the promise of the open sea outside the harbor.
When it's light outside, diners can look out on a graceful patio carved out of the stony hillside at the base of which Eno Terra sits.
His administration was characterized by an economic crisis, however, the bases of which had been laid by his predecessors.
Glass cutting was also practiced in Egypt, primarily for the production of deeply incised small perfume bottles of square sections, the bases of which were often cut into four tapering feet ("molar tooth" bottles).
The presbytery's arcades were supported by eight clustered shafts, the bases of which are still visible, with capitals carved with naturalistic foliage.
And should one completely rule out the hypothesis of an Egypt that, at the end of the day, may find itself with a government that, civilian or not, is a variation of the regime installed long ago by Nasser, the bases of which, fundamentally, will not have changed?
At NF 54, the muscle bundles are situated in the crests of inwardly directed epithelial folds, the bases of which show the rudiments of veins (Fig. 1I).
