Procedural Mesh, Strange Clipping

So I've generated a mesh from code ala Minecraft and have this strange clipping problem that I can't figure out. I've checked and re-checked the vertices, the winding order of the triangles, the UVs, and the normals (whether manually or via RecalculateNormals()), and everything looks correct, however, I feel like I've missed an obvious step.

Any advice on where to look?

Here's a video: http://player.vimeo.com/video/42946293

Here's some example code for one face of a cube:

             # check to the right of a spot and see if it needs squares built upwards (i.e. the spot to the right is higher)
             if (x+1 < len(chunkHeights, 0)):
                 if (chunkHeights[x,y] < chunkHeights[x+1, y]): # if the block to the right is higher...
                     total_blocks_up = chunkHeights[x+1,y]  - chunkHeights[x,y]
                     for b in range(total_blocks_up): # block to the right could be several spots higher
                         # vertices for square
                         vertex_list.Push(Vector3(x+1, h+1*b, y+1))
                         vertex_list.Push(Vector3(x+1, h+1*b, y))
                         vertex_list.Push(Vector3(x+1, h+1+1*b, y))
                         vertex_list.Push(Vector3(x+1, h+1+1*b, y+1))
                           # uvs. (16 textures per side in the texture sheet)          
                         uv_list.Push(Vector2(0/16.0, 15/16.0))
                         uv_list.Push(Vector2(1/16.0, 15/16.0))
                         uv_list.Push(Vector2(1/16.0, 1))
                         uv_list.Push(Vector2(0/16.0, 1))
                          # normals point due left. this is also what's generated by RecalculateNormals()
                         normal_list.Push(Vector3(1,0,0))
                         normal_list.Push(Vector3(1,0,0))
                         normal_list.Push(Vector3(1,0,0))
                         normal_list.Push(Vector3(1,0,0))
                         # triangle list in proper order

                         
                         triangle_list.Push(1+i*4)
                         triangle_list.Push(0+i*4)
                         triangle_list.Push(3+i*4)
                         triangle_list.Push(3+i*4)
                         triangle_list.Push(2+i*4)
                         triangle_list.Push(1+i*4)
                         i += 1 # keep track of triangle order in a big list