Viennetta, but made of minerals instead of vanilla ice cream (efflorescence?)

S. and I recently visited a local landmark-slash-mini-park: Blackhead Point, the site of Signal Hill Tower, a brick structure erected in 1907, subsequently enlarged, and shortly thereafter abandoned.

Each day at 1pm, a large copper sphere (aka time ball) was dropped (after having been hoisted to its maximum height minutes beforehand) for the benefit of seamen aboard vessels in the harbor, to give them something reliable against which to judge the accuracy of their ships’ clocks. The frequency was doubled and new drop times (10am and 4pm) were set in 1920, the uppermost level was added in 1927, and then in 1933 the system was discontinued after it was decided that the adoption of radio communications technology had rendered time balls obsolete.

FUN FACT: The Times Square Ball is a rather better-known time ball and, although used just once a year, one which has managed to endure until the present day. Coincidentally, it too was first used in 1907.

The ball raising and lowering apparatus would have been mounted on the roof and, since no vertical pole is visible, we may safely presume that it’s long since been removed. The cage ladder that extends from a top-floor balcony to the roof remains in place.

The park is on the southern edge of Kowloon and one can ascend a small flight of steps a stone’s throw beyond the tower (this staircase is visible in the foreground of the above image), in the direction of Victoria Harbor, to a brick-paved terrace from which it’s possible to peer across the harbor’s waters at the northern shores of Hong Kong Island.

S. cleverly timed our visit to coincide with one of two very brief periods each day (9-11am and 4-6pm) during which a security guard unlocks and opens the impressive solid wooden doors at the base of the tower and visitors are permitted to enter the completely empty structure and walk up to the the top floor.

When we stepped inside and strode towards the extremely compact wrought-iron spiral staircase, however, it became apparent that the heels of my quite-large-by-local-standards feet would protrude far past the edges of the triangular steps, even where the steps were deepest at the outer edge of the spiral. Shallow stair steps have always been an issue for me in Hong Kong and it’s not unusual to have to turn my toes inwards or outwards to try to get more of the soles of my shoes in contact with something solid, but Signal Hill Tower is an extreme case. The staircase was narrow as well and, as it so happens, I am also relatively broad-shouldered by local standards. Given that the interior of the structure was empty and the third floor’s expected payoff would have been a bit better view of the surrounding area, we decided to pass and began the short walk back to the park entrance.

We’d had an interesting bite-sized outing (learning that time balls had ever been put to use in a practical way was intriguing enough) and we were nearing the gate connecting Signal Hill Garden (the official name for the small park at Blackhead Point) to Minden Row, the public road outside, when something caught my eye. Sections of the narrow pavement and the vertical face of the curb to our right looked cantaloupe-y, as though it had been coated with something reminiscent of the side view of a Viennetta ice cream dessert. Sidenote: TIL that the precise technical term for the pattern that forms on skins of cantaloupes and some other melons is reticulation, that reticulated means net-like, and that it’s a poorly-understood phenomenon.

The two paragraphs that follow describe two ways of reaching the area of interest.

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How to see the weird patches of pavement using Google Street View:

Click through to the Google Maps / Street View rendering of the mouth of the park and, using your mouse or other pointing mechanism, walk through the bollards and uphill to the point where the path curves sharply to the right and there are brick embankments on either side. Then, click-drag to turn your gaze to the left and zoom in on spots where you see bright discolorations on the bricks below and around drainage pipe mouths.

How to see the weird patches of pavement in person, walking out of Signal Hill Garden towards Minden Row:

While you are walking downhill on the asphalt-paved main path leading to the front gate, just before it takes a 60-70 curve to meet Minden Row at a right angle, you’re flanked by chest-high embankments faced with bricks and mortar, interrupted at regular intervals by the small circular mouths of drainage pipes buried in the slopes. Keep your eyes on the slope to your right and look for bright-colored bands extending down the side of the wall to the narrow pavement and curb below. Some of these light/white bands start at pipe holes and others seem to begin at a band of mortar.

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We paused, walked over, and had a closer look. I spent a couple of minutes taking photos including those below.

These are all phone-camera shots, I am not a professional photographer, and I had no clip-on lenses with me. Here is the clearest, closest-up photograph I took of the reticulated deposits on that bit of sidewalk:

Sand seems to be accumulating in the hollows and the top of the encrustation appears to be flat rather than ridged. I wonder whether the flattening is natural or the result of human activity (e.g. periodic removal of build-up with something like a grinder for concrete floors). I suspect the former. Note that the reticulated mineral deposits are unambiguously visible at the same spots on the pavement in the Google Street View images (labeled currently as having been taken in December 2021):

At first, when I’d seen it from a few feet away, I’d thought the concrete was being weathered somehow and the cantaloupe-y look was like the honeycomb patterns of erosion that can develop in old limestone and which can be sped up by increased atmospheric SO_X and NO_X and particulates due to human activities. But rather than being thinner than adjacent unmarred areas, the affected spots seemed a bit thicker.

My layperson’s best guess as to the phenomenon afflicting these bits of pavement and curb is some sort of efflorescence aka lime-leaching, perhaps from unseen concrete present beneath the brick layer. Other sections of embankment closer to the street are surfaced in patched skins of concrete with no brickwork overlay. On the other hand, perhaps not. After all, none of the photos that turned up when I searched for these and related terms even faintly resembled these reticulated/net/cantaloupe-y patterns.

I’m almost curious enough to try to make inquiries, but it occurs to me that there’s a non-negligible chance my interest could be perceived as a complaint or criticism and it might prompt maintenance work that would completely efface the patches in question, an undesirable outcome. For me, the cantaloupe micro-terrains at Blackhead Point will have to remain a mystery for now.