simplexml sorting data

I'm trying to sort an xml file (which I have no control over) alphabetically. Is there a way to do this using simplexml?

Basically I'm trying to create a dropdown list using the xml returned, the dropdown needs to be sorted alphabetically by <description>

From the xml attached this is what I would like to achieve

<select>
<option value="gr-tx">Barryscourt Castle</option>
<option value="ab-hy">Cork Heritage Park</option>
</select>

<locations>
   <location>
    <description>Cork Heritage Park</description>
	<id>ab-hy</id>
  </location>
  <location>
	<description>Barryscourt Castle</description>
    <id>gr-tx</id>
  </location>
</locations>

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