function blink(method,second){
	// time interval
	setTimeout(method,second);
}
function random_imglink(){
	// image src
	var aryImgSrc=new Array();
	aryImgSrc[1]= '/images/Rock-Climbing-in-Clarks-Canyon-California-US.jpg';
	aryImgSrc[2]= '/images/Bouldering-BlkMtn-Idyllwild-Cal-US.jpg';
	aryImgSrc[3]= '/images/Jedi_Mind_Trick.jpg';
	// image title
	var aryImgTitle=new Array();
	aryImgTitle[1]='Jessica Chen sport leading at Spud Boy, Clark Canyon, California, United States.';
	aryImgTitle[2]='Christine Morey bouldering at Black Mountain, Idyllwild, California, US.';
	aryImgTitle[3]='Jessica Chen bouldering at Bishop (Jedi Mind Trick), California, US.';
	// photo by
	var aryImgCredit=new Array()
	aryImgCredit[1]=' Photo by: <a href="http://LifeOfRam.com">Ram Sripracha</a>';
	aryImgCredit[2]=aryImgCredit[1];
	aryImgCredit[3]='Photo by: Akira';
	// random pick image
	var ry=Math.floor(Math.random()*aryImgSrc.length)
	if (ry==0){ ry=2; }
	// compose image html display
	var display='<img src="'+aryImgSrc[ry]+'" alt="'+aryImgTitle[ry]+'" title="'+aryImgTitle[ry]+'" width="510"  height="762" border="0" /><br />';
	display+='<div class="footer">'+aryImgTitle[ry]+aryImgCredit[ry]+'</div>';
	// refresh the image
	document.getElementById('rock_climbing_div').innerHTML = display;
	blink('random_imglink()',4000);
}