I made a terrain generator but for some reason there are random holes in the map sometimes?

I have a terrain generator, and it generates terrain forever. But when it continues to generate terrain for some reason there are random holes in the map, why does it do this?

Here is the code:

local Part = game.ServerStorage:WaitForChild("GrassBlox") --For cloning
Part.Anchored = true
Part.FormFactor = "Custom"
Part.Size = Vector3.new(1, 2, 1)
local seed = math.random(1, 10e6)
local frequency = 2
local power = 10
local resolution = 100
local Iteration = 0

function GenMap(Offset1, Offset2)
for x = 1, resolution do
	wait()
	for z = 1, resolution do
        local y1 = math.noise(
            (x*frequency)/resolution,
            (z*frequency)/resolution,
            seed
        )

		local y2 = math.noise(
            (x*frequency*.125)/resolution,
            (z*frequency*.125)/resolution,
            seed
		)
		
		local y3 = math.noise(
            (x*frequency*4)/resolution,
            (z*frequency*4)/resolution,
            seed
        )
        
		local y = (y1*y2*power*power)+y3
		
        local Part = Part:Clone()
        Part.Parent = game.Workspace
        Part.CFrame = CFrame.new(x + Offset1, math.floor(y + 0.5), z + Offset2)
			
		end
	end
end

while true do
	if not frequency == 2 and not frequency == 0 then
	frequency = math.random(frequency - 1, frequency + 1)
	elseif frequency == 0 then
	frequency = frequency + 1
	elseif frequency == 2 then
		frequency = frequency - 1
	end
	
	if not power == 2 and not power == 10 then
	power = math.random(power - 1, power + 1)
	elseif power == 2 then
	power = power + 1
	elseif power == 10 then
		power = power - 1
	end
	
	Iteration = Iteration + resolution
	GenMap(Iteration, 0)
	seed = math.random(seed - 1, seed + 1)
	wait(10)
end