Time Travel discussion

I am trying to find the name of a book I read a few years ago. It is a time travel romantic book. It is about a scientist that takes a walk on a beach after a party and somehow goes back in time 1 million years ago to a civilization that is more advanced than we are. If anyone remembers this book I would greatly appreciate it.

Do you remember the beach name or the location name?

Any character names? Who was the romantic interest?

I'd like to help find the book, sounds interesting!

I wish I could remember...

Yeah, I've been all over the internet search engines trying to find this silly book..It is just sooo frustrating. Thanks for all of your help.