That sounds like an awful lot of homework for a little one. If you're concerned, you should talk to the teacher and review the school's homework policy.
It's a good idea to think about what kind of homework it is as well - is it revision and practice or does it seem to be material that would have been better covered in class?
To fully inform yourself of what needs to be covered in 1st grade, get yourself a copy of the syllabus for your state. It should outline learning objectives and give you a better idea of where your child should be up to.
Personally, I think an hour is too much after a full day at school. Little children get tired out by a long school day and another hour of being cooped up is too much in my opinion.
Definitely talk to the teacher about his / her reasons for all that homework and don't be afraid to voice your concerns. If the teacher isn't helpful, then talk to the Principal.
NB - I have one (long) hub on homework if you want more info. Lots of parents freak out and start doing it all themselves!