Max File size per Table (1G limit??)

I just browsed to my $PGDATA location and noticed that there are some
tables which has ending of .1

# ls -lahS | egrep '(24694|24702|24926)'
-rw------- 1 postgres postgres 1.0G Sep 3 22:56 24694
-rw------- 1 postgres postgres 1.0G Sep 3 22:52 24702
-rw------- 1 postgres postgres 1.0G Sep 3 22:58 24926
-rw------- 1 postgres postgres 800M Sep 3 22:57 24694.1
-rw------- 1 postgres postgres 161M Sep 3 22:52 24702.1
-rw------- 1 postgres postgres 12M Sep 3 22:58 24926.1

I'm wondering what are these since I've not set up table partitioning
just yet.