Analyze the poem below for its use of imagery and tone, and how they help create the theme.

Analyze the poem below for its use of imagery and tone, and how they help create the theme.
3 pages poem analysis please
Natural Bridge/Rogue River Canyon
By Paul Halupa
Life surges incessantly towards impediment.
Passages narrow and the resultant
End is hard stone.
On the upper Rogue River, the wall is lava, ancient spills
Left by Mazama against the high hills.
I am alone
And my reflection is dominated by water
Coming to impasse, the teeter-totter
Of decision.
The wall of lava and its field might produce a lake
Or bow the river wide around and make
A revision
In its course, delay its certain bubbling intention
To go forward. But it is invention
That is the mark:
The river hits the wall as if to drive it asunder
And finding a chute beneath, dives under
Into the dark.
And in review it would seem, for us, little different.
Difficulties mount, pressures build, a rent
Is in the wall,
And plunging in we find a serene cavernous strength,
And pressed to run its darkness at full length,
We find our all.