article_snippet.sent: Underneath the national park's attractions and walking paths is enough hot rock to fill the Grand Canyon nearly 14 times over.
article_snippet.sent: It alone has a volume 2.5 times that of the Grand Canyon.
article_snippet.sent: But those great magma expanses do not mean that the two hellish hollows could overflow the Grand Canyon with molten rock.
article_snippet.sent: The overwhelming bulk of the two hellish hollows could overflow the Grand Canyon with molten rock magma cavities comprise scorching -- yet solid -- rock, which is hollow, like sponges, and filled with pockets of liquefied rock.
article_snippet.sent: Lava flowed into the breach, filling Lava, which may account for the lack of a deeper crater.
article_snippet.sent: The upper chamber, which caused the historic blasts and is closest to the surface, is 2,500 cubic miles in volume and measures about 19 by 55 miles.
article_snippet.sent: The lower reservoir, which has a volume of 11,200 cubic miles, measures about 30 by 44 miles and is about 16 miles thick.