Answer: 
The features that are evident of the Pacific Ocean's maturity are its ridges and trenches. 
Step-by-step explanation: 
- The Pacific Ocean is the biggest and the oldest ocean on the planet. The existence of huge ridges and deep trenches in this ocean are evident of its maturity. 
- The ridges are a result of prolonged and consistent elevation of oceanic plates and volcanic eruptions under the water for millions of years. 
- The trenches also take a long span of time for their formation and deepening. Thus, the existence of huge ridges and deep trenches prove the maturity of the Pacific Ocean.