Welcome to Gardens by the Bay
Gardens by the Bay is one of Singapore's most iconic attractions, spanning 101 hectares in the heart of Marina Bay. It's a futuristic garden that blends nature with cutting-edge architecture, designed to support Singapore's vision of becoming a "City in a Garden". It's a must-visit destination for nature lovers, photographers, and anyone looking for a unique experience, or an EarthCache!
For this EarthCache we will attempt to identify the topic by comparing two terms — wormkalk and flat-pebble conglomerate. They are closely related, but they're used in slightly different contexts and can reflect subtle distinctions in geology and regional terminology.
Composition, origins and differences
Wormkalk is built from flat sheets of microcrystalline calcite, each slab a relic of fine carbonate mud. Between these sheets, coarse sparry calcite cement drapes like glue, its crystals sparkling against a pale cream backdrop punctuated by rust–orange iron‐oxide stains tracing tiny fractures. By contrast, the flat pebble conglomerate is assembled from flattened quartz pebbles set in a uniform tan quartz sandstone matrix. Its pebbles retain a milky gloss, while the sandy matrix gleams with mixed calcite and silica overgrowths that bind each fragment into a sturdy whole.
Both wormkalk and flat pebble conglomerate share a birth in storm–stirred shallow seas where powerful waves ripped coherent layers from the seafloor. In the wormkalk, violent storms plucked thin carbonate mudstone sheets that shattered into flat clasts, which then settled in chaotic piles. Tidal currents between storms winnowed the finest mud and nudged slabs into subtle alignments before the next upheaval. The flat pebble conglomerate tells a similar story on a siliciclastic shore: quartz pebbles were torn from earlier sandy beds by storm surges, deposited en masse, then tidally reworked into beds of pancake‐shaped clasts within a sandy matrix.
Although both rocks exhibit pancake‐shaped clasts from storm action, wormkalk owes its origin to a carbonate platform, whereas flat pebble conglomerate hails from a quartz‐rich coastline. Wormkalk clasts often show biogenic traces—burrow marks and grazing trails—preserved in the micrite, while flat pebbles remain largely unmarked by life. Cementation also contrasts: pure sparry calcite seals wormkalk's fragments, but the siliciclastic conglomerate carries both calcite and silica cements. Visually, wormkalk's creamy white transforms to tan in the quartz pebbles of the conglomerate, marking their divergent chemical paths.
How to claim this EarthCache?
Send me the following;
1. The text "GCB38NB Burrowed in Time" on the first line.
2. The answers to the following questions;
- Is this wormkalk or flat pebble conglomerate, and what clues support your conclusion?
- Does the boulder before you bear any preserved trace fossils or burrow marks?
- Which mineral assemblage identifies wormkalk in comparison to flat pebble conglomerate?
3. Provide a photo of yourself or a personal item, with one of the guardian lions nearby to prove you have visited the site. Additional photos from your visit to Gardens by The Bay are welcome! *
Note: If you send a selfie via private message, be sure to mention this in your log!
References
* Effective immediately from 10 June 2019, photo requirements are permitted on EarthCaches. This task is not optional, it is an addition to existing logging tasks! Logs that do not meet all requirements posed will no longer be accepted.
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