The Cascades extend from Lassen Peak (also known as Mount Lassen) (3170 m) in northern California to Lytton Mountain (2,049 m) in Canada, just southeast of the confluence of the Fraser and Thompson Rivers. The tallest volcanoes of the Cascades are called the High Cascades and dominate their surroundings, often standing twice the height of the nearby mountains. They often have a visual height (height above nearby crestlines) of one mile (1.6 km) or more. The tallest peaks, such as the 14,411 foot (4,395 m) high Mount Rainier, dominate their surroundings for 50 to 100 miles (80 to 160 km).

The northern part of the range, north of Mount Rainier, is known as the North Cascades in the United States but is formally named the Cascade Mountains north of the Canada – United States border, reaching to the northern extremity of the Cascades at Lytton Mountain. Overall, the North Cascades and southwestern Canadian Cascades are extremely rugged, with many of the lesser peaks steep and glaciated, with valleys quite low relative to its peaks and ridges, resulting in great local relief, and major passes are only about 1,000 m (3,300 ft) high. The southern part of the Canadian Cascades, particularly the Skagit Range, are geologically and topographically similar to the North Cascades, while the northern and northeastern parts - the Coquihalla Range, the name of which is unofficial,^{[citation needed]}, the northern half of the Hozameen Range and most of the Okanagan Range are less glaciated and more plateau-like in character, resembling nearby areas of the Thompson Plateau.

Because of the range's proximity to the Pacific Ocean, precipitation is substantial, especially on the western slopes, with annual accumulations of up to 150 inches (3,800 mm) in some areas—Mount Baker, for instance, recorded the largest single-season snowfall on record in the world in 1999—and heavy snowfall as low as 2,000 feet (600 m). It is not uncommon for some places in the Cascades to have over 200 inches (5,500 mm) of snow accumulation, such as at Lake Helen (near Lassen Peak), one of the snowiest places in the world. Most of the High Cascades are therefore white with snow and ice year-round. The western slopes are densely covered with Douglas-fir, Western Hemlock and Red alder, while the drier eastern slopes are mostly Ponderosa Pine, with Western Larch at higher elevations. Annual rainfall drops to 9 inches (200 mm) on the eastern foothills due to a rainshadow effect.

Beyond the foothills is an arid plateau that was created 16 million years ago as a coalescing series of layered flood basalt flows. Together, these sequences of fluid volcanic rock form a 200,000 square mile (520,000 km²) region out of eastern Washington, Oregon, and parts of Northern California and Idaho called the Columbia River Plateau.

The Columbia River Gorge is the only major break in the American part of the Cascades. When the Cascades started to rise 7 million years ago in the Pliocene, the Columbia River drained the relatively low Columbia River Plateau. As the range grew, the Columbia was able to keep pace, creating the gorge and major pass seen today. The gorge also exposes uplifted and warped layers of basalt from the plateau.

North Cascades

• Coquihalla Mountain (southern British Columbia) — highest peak in the Bedded Range.
• Mount Baker (Near the United States-Canada border) — highest peak in northern Washington. It is an active volcano^[5]. Steam activity from its crater occurs relatively frequently. Mount Baker is one of the snowiest places on Earth; in 1999 the ski area (on a subsidiary peak) recorded the world's greatest single-season snowfall: 1,140 inches (95 feet or 2,896 cm).
• Glacier Peak (northern Washington) — secluded and relatively inaccessible peak. Contrary to its name, its glacial cover isn't that extensive. The volcano is surprisingly small in volume, and gets most of its height by having grown atop a nonvolcanic ridge.

High Cascades

• Mount Rainier (southeast of Tacoma, Washington) — highest peak in the Cascades, it dominates the surrounding landscape. There is no other higher peak northward until the Yukon-Alaska-BC border apex beyond the Alsek River.
• Mount St. Helens (southern Washington) — Erupted in 1980, leveling forests to the north of the mountain and sending ash across the northwest. The northern part of the mountain was destroyed in the blast (1980 Mount St. Helens eruption).
• Mount Adams (east of Mount St. Helens) — the second highest peak in Washington and third highest in the Cascade Range.
• Mount Hood (northern Oregon) — the highest peak in Oregon and arguably the most frequently climbed major peak in the Cascades.
• Mount Jefferson (northcentral Oregon) — the second highest peak in Oregon.
• Three Fingered Jack (northcentral Oregon) — Highly eroded Pleistocene volcano.
• Mount Washington (between Santiam and McKenzie passes) — a highly eroded shield volcano. [2]
• Three Sisters (near the city of Bend, Oregon) — South Sister is the highest and youngest, with a well defined crater. Middle Sister is more pyramidal and eroded. North Sister is the oldest and has a crumbling rock pinnacle.
• Broken Top (to the southeast of South Sister) — a highly eroded extinct stratovolcano. Contains Bend Glacier.
• Newberry Volcano — isolated caldera with two crater lakes. Very variable lavas. Flows from here have reached the city of Bend.
• Mount Bachelor (near Three Sisters) — a geologically young (less than 15,000 years) shield-to-stratovolcano which is now the site of a popular ski resort. (Mt. Bachelor ski area)
• Diamond Peak (south of Willamette Pass)  — a 8,744 feet (2,665 m) volcano composed of 15 cubic kilometres (3.6 cu mi) of basaltic andesite.
• Mount Bailey (north of Mount Mazama)
• Mount Thielsen (east of Mount Bailey) — highly eroded volcano with a prominent spire, making it the Lightning Rod of the Cascades.
• Mount Mazama (southern Oregon) — better known for its Crater Lake, which is a caldera formed by a catastrophic eruption which took out most of the summit roughly 6,900 years ago. Mount Mazama is estimated to have been about 11,000 ft. (3,350 m) elevation prior to the blast.
• Mount Scott (southern Oregon) — on the southeastern flank of Crater Lake. At 8,929 feet (2,721 m) elevation, this small stratovolcano is the highest peak in Crater Lake National Park.
• Mount McLoughlin (near Klamath Falls, Oregon) — presents a symmetrical appearance when viewed from Klamath Lake.
• Medicine Lake Volcano — a shield volcano in northern California which is the largest volcano by volume in the Cascades.
• Mount Shasta (northern California) — second highest peak in the Cascades. Can be seen in the Sacramento Valley as far as 140 miles (225 km) away, as it is a dominating feature of the region.
• Lassen Peak (south of Mount Shasta) — southernmost volcano in the Cascades and the most easily climbed peak in the Cascades. It erupted from 1914 to 1921, and like Mount Shasta, it too can be seen in the Sacramento Valley, up to 120 miles (193 km) away. Lowest Peak because the Cascades extend from it.