LOG4PHPで出力フォーマットを指定しないとログには日時は出力されない
以下はLOG4PHPに渡す設定ファイル（config.xml）の内容

<configuration xmlns="http://logging.apache.org/log4php/">
	<appender name="myAppender" class="LoggerAppenderFile">
		<param name="file" value="c:/phplog/myLog.log" />
	</appender>
	<root>
		<appender_ref ref="myAppender" />
	</root>
</configuration>

設定ファイルを以下に変更して日時を出力指定する

<configuration xmlns="http://logging.apache.org/log4php/">
	<appender name="myAppender" class="LoggerAppenderFile">
		<layout class="LoggerLayoutPattern">
			<param name="conversionPattern" value="%d %-5p %m%n" />
		</layout>
		<param name="file" value="c:/phplog/myLog.log" />
	</appender>
	<root>
		<appender_ref ref="myAppender" />
	</root>
</configuration>

すると以下のエラーが表示された

Warning: date(): It is not safe to rely on the system's timezone settings. 
You are *required* to use the date.timezone setting or the date_default_timezone_set() function. 
In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. 
We selected 'Asia/Tokyo' for '9.0/no DST' instead in C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\php\php\log4php\pattern\LoggerPatternConverterDate.php on line 74 Warning: date(): 
It is not safe to rely on the system's timezone settings. 
You are *required* to use the date.timezone setting or the date_default_timezone_set() function. 
In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. 
We selected 'Asia/Tokyo' for '9.0/no DST' instead in C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\php\php\log4php\pattern\LoggerPatternConverterDate.php on line 74 Warning: date(): 
It is not safe to rely on the system's timezone settings. 
You are *required* to use the date.timezone setting or the date_default_timezone_set() function. 
In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. 
We selected 'Asia/Tokyo' for '9.0/no DST' instead in C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\php\php\log4php\pattern\LoggerPatternConverterDate.php on line 74 Warning: date(): 
It is not safe to rely on the system's timezone settings. 
You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. 
We selected 'Asia/Tokyo' for '9.0/no DST' instead in C:\Program Files\Apache Software Foundation\Tomcat 7.0\webapps\php\php\log4php\pattern\LoggerPatternConverterDate.php on line 74

メッセージに従ってphp.iniに以下を追加して対応

date.timezone = Asia/Tokyo