A wide, steep-sided mountain valley is half submerged by a mass of ice hundreds of feet deep. Although it appears as a still, frigid waste, it flows another few feet (one or two meters) down the valley each day. Dark stripes on the ice surface mark trails of rock debris fallen from valley walls, that have been spread out by the ice motion.
Dimensions The glacier surface is a mile (2 km) across, and extends tens of miles/kilometers along its valley from the joining of smaller glaciers up-valley, down to the sea. The depth of ice here exceeds 300 feet (100 meters).
Although appearing near-flat when viewed from some distance, the ice surface is fractured by deep parallel crevasses running in broad curves across the ice flow. In many places the surface is further broken up into a chaos of elevated and fallen ice blocks.
Broken-up ice blocks are the size of cars or houses, standing 5-20 feet (1.5-6 m) above and below their neighbors.
The ice near the valley walls creeps along more slowly. Different parts of the ice surface ranged along the glacier length will also vary in speed of movement, at least over periods of days and weeks.
An object placed on the glacier surface will be buried under snow and ice as months progress if it is far up-valley, near the glacier source. If it is further down-valley, the surface ice will melt more each year than it builds up, so the object will stay at the surface, and buried objects may emerge.
In crevasses and other ice fractures, it is possible to see ice of an intense blue color. This is the natural color of large masses of pure ice, when pressure, melting, and shearing have eliminated the bubbles of air that commonly make ice look gray or white.
In winter, fallen and drifted snow can mask some of the narrower crevasses.
In summer, many low spots in the glacier surface become ponds or channels of running water. Some still, deep pools transmit the blue hue of ice below. In warm, calm weather, the air will be significantly cooler in depressions on the ice surface.
Meltwater flowing from glaciers can be quite dirty with finely fragmented rock and microscopic algae.
Travel will be slow and difficult on the ice surface (therefore, this may be a nice place to introduce a ticking clock). On fairly flat ice scored with crevasses, characters will need to step carefully, and a route across the glacier, paralleling the main lines of crevasses, will be much easier than a direction that requires passing over them. In areas of broken ice blocks, journeying in any direction will involve constant climbing up and down and/or frequent diversions to work laterally around high obstacles and deep pits.
For large groups or individuals needing to make repeated traverses along the same path, a zip line between raised ice blocks might aid overall speed and bypass particularly difficult parts of a cross-ice trek. However as days pass, the line might need to be played out or somewhat retracted to keep proper tension, as ice connection points move down the valley at different rates.
Some other plot device could highlight consequences of the slow ice movement (e.g., an especially high-standing ice block pressing against a suspension bridge or other structure, a ‘cable-traction device attached to ice and bedrock, important/valuable objects on the ice moving year-by-year closer to a political boundary line).
Given the difficult nature of this ice landscape bounded on both sides by steep, unbroken rock slopes, why might anyone venture onto it? This might be the only available route for cross-country travel or escape, it could be a location for a culture’s rite of passage, or stranded people might need to be rescued there.
A nighttime search party’s lights would have a striking look, reflecting off crevasse edges, casting shadows among broken ice blocks, or glowing through thinner walls of translucent ice.
A crevasse might be a tempting place to hide from view. Dangers there may include unsuspected depth of the fracture (drops of tens of feet/meters are possible), break-through of a false snow floor, a fall of snow or ice from above, or the crevasse filling up with summer afternoon meltwater flow.
Someone who falls into a pool of water will find it difficult to get footing on the ice floor or to climb the slippery walls at pool’s edge.
Floating or rafting on a stream of frigid water on the glacier may be a relatively quick way to travel. However, some streams disappear into pits several feet across, taking the water flow down into ice tubes in the glacier interior.
Hand-to-hand combat might occur on a flat, snowy surface bounded tightly by deep crevasses on each side.
Snow-covered crevasses and snow-filled ice block depressions provide surprise places to fall/sink.
A zone of broken ice blocks presents such a complex local horizon that someone clambering across the glacier surface will have trouble scanning in all directions continuously enough for distant attackers or quarry. as their distant positions briefly come into view.
Explosives could divert directions of summer water flow on the glacier surface, for tactical advantage.
Columbia Glacier, northwest of Prince William Sound, near Valdez, south-central Alaska.