Norris Porcelain Basin - Features on the slope in front of Norris Museum
Two partly overlapping loop trails give access to the thermal features of Norris Porcelain Basin. This makes it a little bit tricky to present the features in a sequence a visitor will encounter them on location. To retain orientation the virtual tour is divided up into three parts:
- Features on the slope in front of Norris Museum
- Features west of the central boardwalk to Pinwheel Geyser (in the direction of Crackling Lake)
- Features east of the central boardwalk to Pinwheel Geyser (in the direction of Porcelain Springs)
Features on the slope in front of Norris Museum:
From Norris Museum the trail leads slightly down to a fork. The steep slope beyond the fork is home of several geysers and fumaroles. Probably the first one to catch the eye by forceful steaming is Guardian Geyser directly at the base of the slope. Actually, the fork of the trail on top of the slope is the best position to observe Guardian. This geyser is known for different modes of activity. In the early 2000s it has sometimes ejected hot water ("water-phase eruptions") up to 9 m (30 feet) high, but from 2005 to the end of 2021 it acted almost exclusively as a forceful steam vent.
Since the end of 2021 Guardian's mode has switched back from steam emissions to intermittent geyser activity, which occurs a few times a year at most.
The similarily strong steaming vent on a hump right (east) of Guardian Geyser is Black Growler Steam Vent. It has never shown any geyser activity, but was featuring the highest surface temperature of 138 °C (280 °F) ever measured in Yellowstone. Strictly speaking, Black Growler is not only a single steam vent, but a collection of one big and several smaller vents, distributed on or near the upper edge of the slope. In course of time there have been many changes of the system, and at least five different major fumaroles have been called Black Growler. One of them even was located across the trail within a patch between the boardwalks.
To the other side (west) of Guardian Geyser, Dark Cavern Geyser occupies the base of the slope. It is a little bit hard to spot, and no matter which position on the trail you choose, the vents of Dark Cavern will always be at least partly obscured either by trees or by its own sinter mound. In the past Dark Cavern often was a frequent performer, but currently eruptions are very rare. Accordingly, the geyserite cone shows already signs of decomposition.
The small mud pots and quiet hot springs on the flat area north of Dark Cavern and Guardian Geyser are collectively called Lewis Mud Pots.
Close to Guardian Geyser and partly embedded in the base of an alcove, Valentine Geyser is nearly impossible to observe from the top of the slope. To take a look at Valentines large cone you have to complete half the loop trail and spot it from the north. The geyser emerged on Valentine's Day in 1907, hence the name. Eruptions of Valentine Geyser are of impressive height up to 30 m (100 feet), but unfortunately very rare.
If you follow the trail down the east side of the slope, you pass Ledge Geyser. Ledge plays from different vents. The hillside vent opposite to the trail can't be missed, because most of the time it shows some weak spraying. Another one, regarded as main vent but currently nearly inactive, is within the ragged sinter structure a few feet to the right. A third one is hidden at the bottom of the pressure pool in front of hillside vent, called Palm Pool. The fourth one sits at the hillside below the trail, and is very hard to spot from there. A slightly better view is given from the north section of the loop trail (see photo). After a long period of almost complete dormancy since 1998 Ledge Geyser eventually erupted on April 18th, 2015.
Further eruptions could be observed until the end of 2022, when Ledge turned into a forceful, permanently spouting steam vent. It appears that Ledge took over (with a little delay) the steam mode formerly displayed by Guardian Geyser and, at least partly, by Black Growler Steam Vent.
The pool northeast of Ledge carries the name Jetsam Pool. Geyser activity was seen in the 1990s, but only on very rare occasions.
Even closer to the trail is Basin Geyser northwest of Jetsam Pool. Basin Geyser was for the last time active in the 1970s.
North of Basin Geyser Scummy Pool is one of the few named blue pools west of the boardwalk.
