Broken Top Loop Trail explores a large volcanic field in Craters of the Moon, Idaho, USA.
From Spatter Cones, the adventure continues along the counterclockwise, 7-mile loop road, to a spur which leads through the Big Sink in Lava Cascades, prior to parking for the trail-heads to the Broken Top, Tree Molds and Wilderness trails.
The first, short hike in this series will be the self-guiding, 1.8 mile (2.9 KM) Broken Top Loop Trail which circumnavigates a cinder cone.
The Broken Top Loop trail initially climbs gentle elevation where long views begin to unfold across Craters of the Moon National Monument. Along the trail, there are 10 numbered markers on the hike up, around and through the freshest lava on the Snake River Plain.
Marker # 1 resides at a depression. This deep tear in the earth sprayed frothy, molten rock high into the air and the adjacent cinder cone formed as cinders fell back to earth.
At Marker # 2, the northern horizon shows the demarcation line between the Craters of the Moon lava field and the Pioneer Mountains. This also marks the north end of the 52 mile-long (83.2 KM) series of fissures known as the Great Rift.
Craters of the Moon National Monument protects nearly all the Great Rift within 750,000 acres of land.
Marker # 3 is a short ¼ mile spur off the main trail to the Big Sink Overlook which is a huge lava flow called the Blue Dragon.
Blue Dragon is one of the youngest lava flows in Idaho at 2,100 years. Brilliant blue glass colors the landscape of this flow. The loop road through the Blue Dragon is obvious.
At Marker # 4, the hike proceeds over cinder which crackles and crunches beneath footsteps. Cinders contain gas bubbles which makes some of them light enough to float on water and thin layers of glass coating the cinders reflect rainbows of light.
Big Southern Butte, which is a massive dome of the lava form of granite, formed about 300,000 years ago when rhyolite lava broke through the layers of dark basalt to form this peak which rises from the plain about 25 miles (40 KM) to the east.
At Marker # 6, the assignment is searching for lava 'bombs'.
When the fissure was erupting, large chunks of lava were thrown high in the air and cooled in-flight into diverse, rock-like shapes which litter the surrounding surface.
Clear evidence exists for the reason this trail is called Broken Top. The flat crust of lava is like a mantle at Marker # 7.
The rise behind the mantle is a pressure ridge. The crust cools and hardens while molten lave continues to flow underneath. Pressure below the roof forces the crust upwards and causes the mantle to bend and break.
At this point along the Broken Top Loop Trail, there exists the option to swing left onto the 4 mile (6.4 KM) Wilderness Trail which leads to molds of upright trees called 'lava trees' and the wilderness beyond.
Reluctantly time will prevent taking advantage of the Wilderness Trail option and this day's effort continues along the Broken Top Loop Trail to Buffalo Caves.
At Marker # 8, gearing up occurs for the only caving experience available on this trip. Exploration of Buffalo Caves will be covered in a separate post.
This post proceeds from the end of exploring Buffalo Caves to Big Cinder Butte at Marker # 9.
A fountain of fire more than 1,500 ft (457 m) high produced the Big Cinder Butte which is 700 ft (213.4 m) high and is the largest cinder cone within Craters of the Moon National Monument.
Towards the end of the Broken Top Loop Trail, the hike proceeds through pahoehoe lava flows.
This Hawaiian word means 'ropy' and this feature is clearly obvious on the loop back to the trail-head for this fascinating learning experience in unusual and starkly rugged and beautiful terrain.
The only trail remaining to be hiked at Craters of the Moon National Monument is the Tree Molds Trail prior to continuing south towards the main hiking objective at Yosemite National Park in California, USA.