I enjoyed the first part of this book but agree with everyone that the ending feels rushed after the leisurely pace of the beginning. And I am kind of confused by the ending too; I think it's supposed to be 'spiritual' rather than scientific and as I see it, the people on the space mission somehow captured a creationist vibration in the sphinx thing (but what was that? everyone says it doesn't look like anything that exists on earth) and then she lets it out at the end. But what is that supposed to accomplish? All I could think of was this Star Trek movie where they drop a device that's supposed to start life on a planet, which destroys everything that's there before it starts the cycle of creation.
One thing I did like was that in the history of the book, after the green revolution, industry used the new eco-awareness to hold the world to ransom; as a bit of an eco-skeptic myself I'm always appreciative of anything that doesn't toe the usual line on these issues.