Mine

for i=1,5 do

 for i=1,10 do

  if not turtle.detectDown()
   then turtle.select(2)
    turtle.placeDown()
  end

  if not turtle.forward() then
   repeat
    turtle.dig()
    sleep(0.2)
   until turtle.forward()
  end

 end

 turtle.select(1)
 turtle.turnLeft()
 turtle.turnLeft()
 turtle.place()
 turtle.turnRight()
 turtle.turnRight()

end

turtle.digUp()
turtle.up()
turtle.turnRight()
turtle.turnRight()

for i=1,50 do

 if not turtle.forward() then
  repeat
   turtle.dig()
   sleep(0.2)
  until turtle.forward()
 end

end

turtle.down()
turtle.turnRight()
turtle.turnRight()