“Yes,” she assented, and then timidly, “it is 3,213 miles wide, is it not?”
“Yes,” he said, “and 1,781 miles deep! It reaches from the forty-ninth parallel to the Gulf of Mexico.”
“Oh,” cried the girl, “what a vivid picture! I seem to see it.”
“Its major axis,” he went on, his voice sinking almost to a caress, “is formed by the Rocky Mountains, which are practically a prolongation of the Cordilleran Range. It is drained,” he continued—
“How splendid!” said the girl.
“Yes, is it not? It is drained by the Mississippi, by the St. Lawrence, and—dare I say it?—by the Upper Colorado.”
Somehow his hand had found hers in the half gloaming, but she did not check him.
“Go on,” she said very simply; “I think I ought to hear it.”
“The great central plain of the interior,” he continued, “is formed by a vast alluvial deposit carried down as silt by the Mississippi. East of this the range of the Alleghanies, nowhere more than eight thousand feet in height, forms a secondary or subordinate axis from which the watershed falls to the Atlantic.”
He was speaking very quietly but earnestly. No man had ever spoken to her like this before.