turtle.refuel()

while turtle.detectDown() do
    if turtle.detect() == true then
        turtle.dig()
        turtle.digUp()
        turtle.forward()
    if turtle.detect() == false then
        turtle.turnLeft()
        turtle.dig()
        turtle.digUp()
        turtle.forward()
	if turtle.detectDown() == false then
		turtle.place(4)
end
end
end
end