The following links will take you to the vaious different fossil phylums that can be found in the Government Canyon area. Note that the phylum Mollusca is very large and has been subdivided into 3 classes: Pelecypods (clams), Gastropods (snails), and Cephalopods (squids). 

There is also a few links to other useful areas below.

Pelecypods (clams)	Molluscs (clams, snails, squids)
Information	Cephalopods (squids, octopi)
Pictures	Information
Echinoderms (Starfish, Sea Urchins)	Pictures
Information	Pelecypods (clams, oysters)
Pictures	Information
Poriferas (Sponges)	Pictures
Information	Gastropods (snails, slugs)
Pictures	Information
Brachiopods (Lingulides)	Pictures
Information	Bryozoans ("Moss animals")
Pictures	Information
	Pictures

Links:

Tapestry of Time from the United States Geologic Survey

Geologic Time Scale