Gates
The first Gate was created by the Drow to enable them to travel via the Natural Gate of Water to Everinstar (then Eriador) swiftly, emerging in Crag Un.
Lastar became aware of the Natural gates just after his first encounter with Orcus in 525. He realised that there might be an elemental link with the gems and rings of power. He encouraged the building of the Minas – recognising that any Plane dweller could arrive at the Prime unannounced. Lastar had also become aware of the Drow, through council with Gelmir, and realised them to be a threat. For their part the Drow recognised that Lastar could use the gate at Crag Un to attack their dwindling power base at Nagrad. The Drow changed the Gate to point toward the Plane of Fire, making it impossible to use. In 562, Gundleus found the Gate at Tiris. Lastar guessed correctly what it had been and was worried that others may manipulate the natural gates in the same way.
Having listened to the Dwarves he realised that the natural gates were within their halls – apart from Water which he guessed the Drow would wish to reopen at some point in the future. Concerned what might come through, Lastar set about putting a control mechanism in place – the pentagrams - and ensuring they were under constant surveillance – the palantirs. The Dwarves were commissioned to build the Minas in their defence – both from within and without. He also needed to ensure that the gates could not just be shifted from Plane to Plane as the Drow had done, so he built the controlling pentagram in Sutur.
Lastar realised that the Gates might be of great benefit in advancing his knowledge and that of his friends in their direst time of need. He encouraged the Dwarves to explore beyond the Prime, and gave them the Rings to protect them from the elements. In this way, they would be determined to protect the Gates, guarding them jealously. [Dor and Ishtur would use their rings mainly to protect from anything that might come through…] The position of the gates at the beginning of the first age was:
Air – Zem’s highest peak
Earth – Aarda
Fire – Malek
Water – Nagrad
Ethereal – Olga
Astral - Maedus
Negative – Zundar
Positive – Malek
After Lastar had set up his pentagrams little had changed except the swap between fire and water the Drow had brought about:
Air - Emras; Zem (living in Minas Emras) receives the blue Ring of Air.
Earth - Aarda; Hamar (living in Minas Aarda) receives the green Ring of Earth.
Fire - Tiris; Dor (living in Minas Tiris) receives the indigo Ring of Water.
Water - Morgul; Ishtur (living in Minas Morgul) receives the red Ring of Fire.
Astral - Maedus
Ethereal - Olga
Negative - Zundar
Positive - Blaven's Pool
Sutur - Control
Lastar realised that there were positive and negative influences but he was never quite sure what could be done about them – hence no Minas was built at Zundar and the Positive Plane at Malek was not discovered [before Blaven.]
Lastar’s Pentogram
You notice that the wheel moves around to each point in turn at each Age thus the dwarven symbols for each element would move and the one that pointed toward the gate indicated the inner plane to which it was aligned.
When each Minas was created - largely to protect the gates - they were aligned to an element and to the ethereal - Olga symbol. (Where a natural gate opened to the ethereal and the symbol for Olga would point at the Gate.) You correctly identified that the movement of the anvil, star/sun, eye and tree represented the +'ve and -'ve age that the gate was used - but there is another important aspect here which links to the book and palantir which you'll need to consider. You are quite correct that the 6 Minas were aligned to elements (you deduced this during one of the other BWs) - understanding that Morgul had something to do with fire and Tiris, water...Clearly, after Lastar left the Prime they started to move - was that intentional or as a result of him leaving? (NB - it was because the Palantirs were moved)
There are 7 Dwarven Houses (each represented with a symbol and a colour) and Orodruin's folk but only 6 Minas (excluding Sutur whose tower was made to resemble a Minas).
You are correct that Zundar linked to the Negative - not Hel, who lives in Nilfheim (a part of Hades - which might help with the long poem about seasons) - and is occasionally reflected in static images of pentograms like the one in Cran's lookout.
You are also correct that Maedus links to the Astral and Olga the ethereal. You might have noticed that on most active pentograms, Maedus was missing as it is only required for travel to Outer Planes.
You used a Pentogram at Sutur to travel to Aarda - Lanzi's arrangement of braziers and the Book of the Inner Planes, which tells Lanzi the dweomer to use, enables the ring to move - in either direction - to get the appropriate destination at the point of the Pentogram which faces the visible gate. This was the way Lastar, and others, controlled the gates to the inner planes.
He had no control over the natural gates in Amorsland but Lanzi has seen similar braziers, pentograms and palantirs - they just did not have the dwarven symbology that you have become aware of. What you have noticed is that the outer ring moves clockwise at each changing age and the inner symbology flips 180 degrees. (Have a recap to decide what the inner symbology meant to you - the tree, eye, star/sun, anvil and book.) What does the wheel on which the dwarven symbols mean and why does it rotate?
If you could work out the starting positions - when Lastar first made the portal system - you'll have cracked it. Clearly, if you need to, you can check the date with the wall carvings that are ever present in Dwarrowdelfs. There should have been 6, rotations. The impact of using a gate to move between Minas changes nothing - it will revert to its date aligned posture; however, diverting a gate does change the mechanics as you have seen.
Between the Minas - Ethereal
Symbol in the middle = current location
Ring outside (sometimes absent) = Astral
Other symbols represent the other Minas
Olga symbol = Ethereal
To move between the Minas place one brazier on the Ethereal (Olga) symbol and another on the desired Minas destination.
Ethereal gate opens step through - Voila !
Aligning the Gate to a Plane To align the gate to another plane: Light 4 braziers placing them over the elemental symbols to cover them Place the required Tome of the Plane (part of the Codicil) on the symbol of the Book in the centre. Gate will shift to the desired plane