It's not the snakes at the bottom of the long drop that are the problem. They don't much like excrement and tend to just try to climb up the wall. It's the African bull frog that's the very real danger.
He lives at the bottom of the drop.
http://www.rollinghillswildlife.com/...rog,-Bubba.gif
It has very sharp teeth and is violently and voraciously carnivorous. It is highly aggressive, weighs up to two kilos and can jump like a Jack Rabbit. It's always hungry and always wants to get to the food source. Shooting them between your own legs as they are on the jump has led to some serious accidents which have provided the bully frog, from time to time, with more delicious food than it thought it would sink it's teeth into on reaching the pink, or blacksource provider.
All long drops in Africa must be considered to have snakes and Pyxicephalus adspersus in them. You can tell which is coming for you because the African Bullfrog makes a sticky slurpy noise as he unsticks himself from the mounds of dung in which he lives and stirs himself into an anal upward trajectoried rabid rectal rocket. Watch out too for crocodiles waiting patiently just out of lanter range.