sub identify_changed_dirs {
    my @dirs = "";
    my $touchfile    = $gcfounds2mysqlconfig{''}{'touchfile'};
    my $gcdir        = $geologconfig{''}{'directory'};

    # append the sub directory "found" to the working directory
    $gcdir .= "/found/";

    # determine the timestamp of the previous script run
    my $timestamp = ( stat("$touchfile") )[9];

    # change the directory to $gcdir
    chdir($gcdir) or die "Error: Cannot change to working directory!\n   $!";
    print "DEBUG 1: changed to the working directory\n$gcdir\n";

    # open directory and read all sub directories
    opendir( DIR, '.' )
      or die "Error: Working directory cannot be opened!\n   $!";
    my $i = 0;    #index variable
    while ( my $subdir = readdir(DIR) ) {

        # we skip the two special directories ./ and ../
        if ( $subdir eq "." )  { next; }
        if ( $subdir eq ".." ) { next; }

        # seems unneccessary to calculate the full path!
        # my $fullpath = $gcdir . $subdir . "\/";
        
        # test whether the current object is a directory
        if ( -d $subdir ) {
            
            # calculate the mtime of the $subdir
            my $subdir_mtime = ( stat("$subdir") )[9];
            
            if ( $subdir_mtime > $timestamp ) {
                $i++;    #index will be raised when we find a changed directory
                # TODO TODO: delete this print
                print "Untersuchung fand $i. geändertes Verzeichnis!\n";

                # Now we push this sub directory in the array!
                # Splices replaces the push here!
                splice( @dirs, @dirs, 0, $subdir );
                print @dirs[-1] . "\n";
            }
        }
        print ".\n";

        # TEST Early exit for testing
        # if ($i == '10'){last;};
    }

    # closes the workdir at end of the main loop
    closedir(DIR);
    
    return (\@dirs);
    
    # --> DEBUG:  close early
    # exit;
}