if(document.images) {
		//	allocate image array
		imageArray = new Array();
		imageArray[0] = new Image();
		imageArray[1] = new Image();
		imageArray[2] = new Image();
		imageArray[3] = new Image();
		imageArray[4] = new Image();
		imageArray[5] = new Image();
		
		//	assign images to image array
		imageArray[0].src = "images/thumb_images_large_1.jpg";
		imageArray[1].src = "images/thumb_images_large_2.jpg";
		imageArray[2].src = "images/thumb_images_large_3.jpg";
		imageArray[3].src = "images/thumb_images_large_4.jpg";
		imageArray[4].src = "images/thumb_images_large_5.jpg";
		imageArray[5].src = "images/thumb_images_large_6.jpg";
		
		//	allocate caption array
		captionArray = new Array();
		captionArray[0] = 'Black spruce (<span style="font-style:italic">Picea mariana</span>) bog in northern Alberta.  Peatlands like this are a dominant feature in Alberta\'s boreal region, and are a dominant component of Alberta\'s total wetland area.';
		captionArray[1] = 'Aerial view of a patterned fen.  Like bogs, these peatlands are a common feature in Alberta\'s Green Area.  The exact cause of the intricate banding pattern in such peatlands is not fully understood.';
		captionArray[2] = 'A marsh in the prairie region of Alberta.  Marshes are the most common type of wetland seen in the settled areas of the province.';
		captionArray[3] = '<span style="font-style:italic;">Aulacomnium palustre</span>, a species of moss common to boreal peatlands.  Litter formed by the death of mossess is the main component of peat formed in Alberta.';
		captionArray[4] = 'Aerial view of an area dominated by shallow open-water wetlands.  Open-water wetlands are common in the glaciated prairie region, extending through the Prairie Provinces and into the northern prairie states.';
		captionArray[5] = 'A red-winged blackbird (<span style="font-style:italic;">Agelaius phoeniceus</span>) with grasshoppers on a cattail (<span style="font-style:italic;">Typha latifolia</span>).  Both are encountered in and around marshes and shallow open-water habitats in Alberta.';
	}
	
	//function to swap images on hover
	function swapImage(target,index) {
		if(document.images) {
		document.images[target].src = imageArray[index].src;
		}
	}
	
	function swapCaption(target, index){
		document.getElementById(target).innerHTML=captionArray[index];
	}