Grimrock

I've been to level 8 and found a note showing where the button is on level 7 but when I press it there is just a click and I can't see that anything has opened. Could you tell me what this button does.
Also there is a room with three pits in the middle and a portal and corridor visible on the other side but I can see no way to get across.

it open doors/wall nearby, those door will shut automatically so u have to be quick.

I found what it opened, just had to lok around a bit more.
But what about those pits?