A Doomed Pilgrim in the Ruins of the Future

Normally such giant arachnids would not be so easily toppled, but you were lucky, you hit the spider as it leaped towards you and were able to push it into the portal.

Giant spiders and portals do not mix, opposing magical fields is the general theory. Whatever the reason, the collision triggered an explosion which ripped through the space between worlds. Something like a cannonball fired through a particularly weak tissue. The result, of course, is a gigantic, uncontrolled trans-location event. This means that you, what remains of that spider, and several tons of desert sand and small spiders are now raining down on a very unfamiliar landscape.

I flail wildly as I plummet! There doesn't seem to be much else I can do.
How high up am I? What am I going to land on?
Anyone should answer the first question, and then someone else should answer the second.

(Hey, how many of you are there who are following this topic but haven't been giving answers? Go ahead and post "No gods watch over you", would you? I'm curious to know who's here.)