How to reset the high_resolution_clock::time_point

I'm develoiping a class Timer that some of its members are of type high_resolution_clock::time_point where time_point is defined as typedef chrono::time_point<system_clock> time_point;

Question

What is the default value of this object?

I need to be aware of this value from couple of reasons:

1. Know if member was initialized
2. Implement Timer::Reset() function