He starts with a general overview of the area to be explored, looking at the valley of the Colorado; the regions mesas and buttes; its mountains and plateaus; and its cliffs and terraces. As you may know, I'm a great believer in making geology understandable to the interested layman in the way Wayne Ranney writes for example. John Wesley Powell seems of like mind too, as is shown in this explanation of the arrangement of four lines of cliffs that extend from east to west across the region:
Place a book before you on a table with its front edge toward you, rest another book on the back of this, place a third on the back of the second and in like manner a fourth on the third. Now the leaves of the book dip from you and the cut edges stand in tiny escarpments facing you. So the rock-formed leaves of these books of geology have the escarpment edges turned southward while each book itself dips northward and the crest of each plateau book is the summit of a line of cliffs.
Go on, try it! Then turn to page 90 of the book and look at the 'Section and birds eye view" I love the explanation and the simple practical exercise. Brilliant!
Chapter 5 sees the start of the record of the expedition. What follows is a truly absorbing account of the triumphs and disasters as they progressed. What really pours out of the pages of this account is Powell's passion for geology and his love of the entire region. Despite the battering he and his fellow explorers endured at times and the hardships that they experienced, his determination to succeed never wavered. Clearly some of his party did not share his belief that they could succeed in completing the journey and three made the decision to leave and 'take their chances'. An unwise move as it turned out as they were to perish at the hands of hostile Indians. Amazingly, Powell was to meet the killers of his colleagues a year or so later in his follow up expedition to the Uinta region and appears not to condemn them for their actions.
I would recommend having a good map of the american south-west or better still, Wayne Ranney's book 'Carving Grand Canyon' at your side when reading this book in order to better track Major Powell' progress. Not all of the names that Powell gave to the multitude of features he encountered have been adopted in the long term, but most certainly have.
I will leave you with John Wesley Powell's closing remarks as he reflected on the experience:-
You cannot see the Grand Canyon in one view, as if it were a changeless spectacle from which a curtain might be lifted, but to see it you have to toil from month to month through its labyrinths. It is a region more difficult to traverse than the Alps or the Himalayas, but if strength and courage are sufficient for the task, by a years toil a concept of sublimity can be obtained never again to be equaled on the hither side of Paradise.