diff --git a/terranostra.lisp b/terranostra.lisp
index ea802f5..b8cd071 100644
--- a/terranostra.lisp
+++ b/terranostra.lisp
@@ -87,6 +87,7 @@
 
 (defun create-mountains (world &optional (montaneity 2))
 	"Create mountains and hills. Montaneity determines number and height."
+	;;XXX Takes too long to calculate if world size > 100
 	(do ((n 0 (1+ n)) (npeaks (random (* (/ montaneity 500)
 										  (* (length world)
 											  (length world))))))
@@ -96,24 +97,31 @@
 
 (defun create-peak (xcoord ycoord height montaneity world)
 	"Create a mountain peak at the specified location"
+	;;TODO Can I make this more computationally efficient?
+	(unless (< (patch-alt (coord xcoord ycoord world)) height)
+		(return-from create-peak))
 	(format t "~&Creating a peak of ~Sm at ~S/~S" height xcoord ycoord)
 	(setf (patch-alt (coord xcoord ycoord world)) height)
+	;; Process concentric squares in increasing distance from the peak
 	(do ((dist 1 (1+ dist)) (levelp NIL))
 		(levelp)
 		(setf levelp T)
 		(do ((x (- xcoord dist) (1+ x)))
 			((> x (+ xcoord dist)))
 			(do* ((y (- ycoord dist) (1+ y))
+					 ;; Get the current patch and its center-side neighbour
 					 (p (coord x y world) (coord x y world))
 					 (np (when p (neighbour p
 									 (dir2patch x y xcoord ycoord) world))
 						 (when p (neighbour p
 									 (dir2patch x y xcoord ycoord) world))))
 				((> y (+ ycoord dist)))
+				;; Only calculate existing patches that haven't been done yet
 				(when (and p (or (= (abs (- xcoord x)) dist)
 								 (= (abs (- ycoord y)) dist)))
 					(let ((new-alt (- (patch-alt np)
 									   (random (* montaneity 5)))))
+						;; Eventually, a hill levels out
 						(when (and (> new-alt *base-height*)
 								  (> new-alt (patch-alt p)))
 							(setf (patch-alt p) new-alt)
@@ -123,7 +131,7 @@
 	"Create valleys through streams. Aqueousness determines their number."
 	(do* ((n 0 (1+ n)) (size (length world))
 			 (x (random size) (random size)) (y (random size) (random size))
-			 (nstreams (random (* (/ aqueousness 100) (* size size)))))
+			 (nstreams (random (* (/ aqueousness 500) (* size size)))))
 		((= n nstreams))
 		(format t "~&Creating a stream from ~S/~S" x y)
 		(create-stream x y world)))

diff --git a/terranostra.lisp b/terranostra.lisp
index ea802f5..b8cd071 100644
--- a/terranostra.lisp
+++ b/terranostra.lisp
@@ -87,6 +87,7 @@
 
 (defun create-mountains (world &optional (montaneity 2))
 	"Create mountains and hills. Montaneity determines number and height."
+	;;XXX Takes too long to calculate if world size > 100
 	(do ((n 0 (1+ n)) (npeaks (random (* (/ montaneity 500)
 										  (* (length world)
 											  (length world))))))
@@ -96,24 +97,31 @@
 
 (defun create-peak (xcoord ycoord height montaneity world)
 	"Create a mountain peak at the specified location"
+	;;TODO Can I make this more computationally efficient?
+	(unless (< (patch-alt (coord xcoord ycoord world)) height)
+		(return-from create-peak))
 	(format t "~&Creating a peak of ~Sm at ~S/~S" height xcoord ycoord)
 	(setf (patch-alt (coord xcoord ycoord world)) height)
+	;; Process concentric squares in increasing distance from the peak
 	(do ((dist 1 (1+ dist)) (levelp NIL))
 		(levelp)
 		(setf levelp T)
 		(do ((x (- xcoord dist) (1+ x)))
 			((> x (+ xcoord dist)))
 			(do* ((y (- ycoord dist) (1+ y))
+					 ;; Get the current patch and its center-side neighbour
 					 (p (coord x y world) (coord x y world))
 					 (np (when p (neighbour p
 									 (dir2patch x y xcoord ycoord) world))
 						 (when p (neighbour p
 									 (dir2patch x y xcoord ycoord) world))))
 				((> y (+ ycoord dist)))
+				;; Only calculate existing patches that haven't been done yet
 				(when (and p (or (= (abs (- xcoord x)) dist)
 								 (= (abs (- ycoord y)) dist)))
 					(let ((new-alt (- (patch-alt np)
 									   (random (* montaneity 5)))))
+						;; Eventually, a hill levels out
 						(when (and (> new-alt *base-height*)
 								  (> new-alt (patch-alt p)))
 							(setf (patch-alt p) new-alt)
@@ -123,7 +131,7 @@
 	"Create valleys through streams. Aqueousness determines their number."
 	(do* ((n 0 (1+ n)) (size (length world))
 			 (x (random size) (random size)) (y (random size) (random size))
-			 (nstreams (random (* (/ aqueousness 100) (* size size)))))
+			 (nstreams (random (* (/ aqueousness 500) (* size size)))))
 		((= n nstreams))
 		(format t "~&Creating a stream from ~S/~S" x y)
 		(create-stream x y world)))
diff --git a/visualize.R b/visualize.R
index 4dceb27..2fad993 100644
--- a/visualize.R
+++ b/visualize.R
@@ -17,7 +17,8 @@
     }
 }
 
-jpeg(paste0(world, "_iso.jpg"), width=720, height=720)
+l = 720*(length(w)/100)
+jpeg(paste0(world, "_iso.jpg"), width=l, height=l)
 persp(1:(length(w[,1])), 1:(length(w[1,])), as.matrix(w), axes=F,
-      theta=110, phi=50, expand=0.4, col=cols, box=F, shade=0.3)
+      theta=110, phi=50, expand=0.4, col=cols, box=F, shade=0.5, border=NA)
 dev.off()