systemd/docs/var-log

You are looking for the traditional text log files in @VARLOGDIR@, and
they are gone?

Here's an explanation on what's going on:

You are running a systemd-based OS where traditional syslog has been
replaced with the Journal. The journal stores the same (and more)
information as classic syslog. To make use of the journal and access
the collected log data simply invoke "journalctl", which will output
the logs in the identical text-based format the syslog files in
@VARLOGDIR@ used to be. For further details, please refer to
journalctl(1).

Alternatively, consider installing one of the traditional syslog
implementations available for your distribution, which will generate
the classic log files for you. Syslog implementations such as
syslog-ng or rsyslog may be installed side-by-side with the journal
and will continue to function the way they always did.

Thank you!

Further reading:
        man:journalctl(1)
        man:systemd-journald.service(8)
        man:journald.conf(5)
        http://0pointer.de/blog/projects/the-journal.html