present the appearance of a solid wall of that precious metal except
where it was broken by outcroppings of ruby, emerald, and diamond
boulders--a faint and alluring indication of the vast and unguessable
riches which lay deeply buried behind the magnificent surface.

But what caught my most interested attention at the moment that the
sun's rays set the cliff's face a-shimmer, was the several black
spots which now appeared quite plainly in evidence high across the
gorgeous wall close to the forest's top, and extending apparently
below and behind the branches.

Almost immediately I recognised them for what they were, the dark
openings of caves entering the solid walls--possible avenues of
escape or temporary shelter, could we but reach them.

There was but a single way, and that led through the mighty, towering
trees upon our right. That I could scale them I knew full well,
but Tars Tarkas, with his mighty bulk and enormous weight, would
find it a task possibly quite beyond his prowess or his skill, for
Martians are at best but poor climbers. Upon the entire surface
of that ancient planet I never before had seen a hill or mountain
that exceeded four thousand feet in height above the dead sea
bottoms, and as the ascent was usually gradual, nearly to their
summits they presented but few opportunities for the practice
of climbing. Nor would the Martians have embraced even such
opportunities as might present themselves, for they could always
find a circuitous route about the base of any eminence, and these
roads they preferred and followed in preference to the shorter but
more arduous ways.