"which underlies" is a grammatically correct and commonly used phrase in written English.
It is typically used to refer to a hidden or underlying cause or basis of something. Example: The success of this company is due to its strong leadership, which underlies all of its decisions and strategies.
The science of demography, which underlies all marketing and advertising, is just keeping pace.
Take, for instance, the Ogallala aquifer, which underlies eight states from Nebraska to Texas.
The general and specific features of plant metabolism ultimately derive from oxygenic photosynthesis, which underlies the autotrophic nutrition of plants.
Britain is a signatory to the European Convention on Human Rights, which underlies the powers of the Strasbourg court.
In particular, it is unclear how a revaluation would correct China's savings-investment imbalance, which underlies that surplus.
The best-understood force, however, is the electromagnetic force, which underlies the related phenomena of electricity and magnetism.
Horse Heaven, in short, is written on the purest Marxist principles, and its author wants us to know the economic basis which underlies the slowly gathering action.
3) Thirdly, the culture which underlies good child protection is one of co-operation and collaboration and of partnership working across agency boundaries and between professionals.
But both are ways of addressing the question of what sex is for, which underlies all the disputes about gay marriage.
Deep learning, for example, which underlies technologies from Siri to Google Translate, uses several interconnected processing layers, modelled after the neuronal strata that compose the cortex.
There he began writing stories which became The Silmarillion, the legendary history of Middle-earth which underlies The Hobbit and The Lord of the Rings.
