Modern cover-collapse sinkhole development in the Brooksville Ridge of west-central Florida uncovered paleokarst solution features filled with Miocene Peace River Formation sediments. Sedimentary structures in this paleokarst fill included a 70 cm-thick package of sub-rounded and moderately well-sorted quartz sandstone, and indurated with poikilotopic calcite cement—confirmed using X-ray diffraction (XRD). The morphology of the sediment package includes mm-scale compositional banding inside cm-scale ‘plops’, akin to types of commercial aquarium stone. Scanning electron microscopy (SEM), energy-dispersive X-ray spectra (XEDS), and portable X-ray fluorescence (pXRF) measurements reveal that metal oxides create the compositional banding and that the grains are frosted with kaolinite–montmorillonite clay. The shape of this ‘plopstone’ deposit, the compositional banding, and structures associated with soft-sediment deformation indicate Stokes Law throughfall in a near-stagnant sub-aqueous setting, with ‘plops’ held together by the cohesion of clay—like kinetic sand. Following deposition, density separation occurred during extensional strain, and cementation progressed slowly in calcite-saturated waters. Collectively, this ‘plopstone’ represents a likely product of sand raveling common during the development of cover-subsidence sinkholes.

佛罗里达州中西部布鲁克斯维尔山脊的现代覆盖塌陷天坑开发揭示了充满中新世和平河组沉积物的古岩溶溶液特征。这个古岩溶填充物中的沉积构造包括一个 70 厘米厚的亚圆形和中等分选石英砂岩，并用异质方解石胶结物加固——使用 X 射线衍射 (XRD) 证实。沉积物包的形态包括厘米级“扑通”内的毫米级成分带，类似于商业水族馆石的类型。扫描电子显微镜 (SEM)、能量色散 X 射线光谱 (XEDS) 和便携式 X 射线荧光 (pXRF) 测量表明，金属氧化物产生了成分条带，并且晶粒被高岭石-蒙脱石粘土磨砂。这种“plopstone”矿床的形状，与软沉积物变形相关的成分条带和结构表明，斯托克斯定律在近乎停滞的水下环境中通过，“扑通”通过粘土的凝聚力（如动力沙子）保持在一起。沉积之后，在拉伸应变期间发生密度分离，并且在方解石饱和的水中胶结作用进展缓慢。总的来说，这种“泥石”代表了在覆盖沉降天坑开发过程中常见的沙子散开的可能产物。