Questions & Answers about Dit gebergte is heel oud.
If specific mountain ranges like the Alps take a plural verb, why does gebergte take the singular verb is?
Even though it refers to multiple mountains, the generic word gebergte (mountain range) is a singular collective noun. Therefore, it takes the singular verb is. This contrasts with geographical proper names of mountain ranges in Dutch, which are almost always plural and take a plural verb (like de Alpen zijn or de Andes zijn).
Why do we use dit instead of deze for gebergte?
Gebergte is a neuter noun (a het-word), so it requires dit (this). A highly useful rule of thumb at this level: almost all collective nouns created with the ge- ... -te structure (like het gebergte, het geraamte, het gedeelte) are always het-words.
How does the structure of the word gebergte give away its exact meaning?
It is built directly from the root noun berg (mountain). By surrounding it with the prefix ge- and the suffix -te, Dutch creates a collective noun meaning a group or collection of that root. So, a single mountain is a berg, but a whole connected system is a gebergte.