Watkins, Joel S. <br/><br/>
Our geological environment / 
Joel S. Watkins, Michael L. Bottino, Marie Morisawa 
 - Philadelphia :  W. B. Saunders,  1975 
 - 519 p. :   ill. ;   26 cm. 
<br/><br/>p. 501-508 
<br/><br/><label>ISBN: </label>0721691331 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geology<br/>Environmental protection