Iceberg Canyon, Colorado River Looking Above, c. 1871. Timothy H. OSullivan served on the first and last seasons (1871-73) of the geographical expedition, led by Lieutenant George Montague Wheeler, to explore and map lands west of the 100th meridian. Wheeler sought an inland passage for troops from Idaho and Utah southward to Arizona and desired to document the topography to benefit future settlement. OSullivan's unequaled experience in the field earned him a boat of his own, Picture, from which he slowly explored the canyons from his low vantage point on the Colorado River. In this carefully composed picture of Iceberg Canyon, he seamlessly blended documentary and aesthetic interests, bringing formal and geological order to what is perhaps his best photograph taken along the Colorado. Contemplating the beautiful scenery, the centrally positioned, seated figure introduces human participation to a scene of geological wonder.