Found at the base of The Great Hollow, Ash Lake is the geographical lowest point in Lordran, although possibly just a metaphorical journey.
This endless stretch of bottomless water, archtrees and curious beams of light is an ash-strewn shore that hold remnants of giants and a Hydra still swims along its banks. At the end of this area stands the last of the everlasting dragons, the Stone Dragon.
In the opening cinematic there is a panning shot of Ash Lake, and the narrator says,
In the Age of Ancients, the world was unformed, shrouded by fog.
A land of gray crags, archtrees, and everlasting dragons.
When the video shows an archtree, and the narrator continues,
Then there was fire
The ashes on the shore therefore may be from that fire mentioned here.
The giant trees in Lordran are distant offspring of the great stone archtrees. Items, such as the Caduceus Round Shield and made from them inherit their properties and can greatly reduces magic damage:
Warrior's Round Shield
Round wooden shield crafted in Lordran.
Decorated with the ancient Labrys axe.
The giant trees in Lordran are distant offspring of the great stone archtrees.
This shield inherits their properties, and the wood reduces magic damage.
Demon's Great Hammer
Demon weapon built from the stone archtrees.