I am reading a children's novel, El león, la bruja y el ropero, translated into Spanish by the Chilean editorial group Andrés Bello. I came across a form of ver that I can't explain. In context, several children are walking along the top of a narrow dam in the winter:
A un costado se encontraba, al mismo nivel, esa gran superficie helada; y al otro veíase una brusca caída hacia el fondo del río.
This looks like a passive se, paralleled by se encontraba, so I would have written se veía, but that's not what is found here. I'm speculating that it's related to the archaic/literary érase (as in "érase una vez"), but I'm not sure how.
What is this construction called? What rules govern it (only certain verbs, only imperfect indicative, etc.)?
¿Cómo se llama la forma gramática de la palabra veíase en el pasaje supra? Respuestas en español están bienvenidas también.