In the tropical rocks, the dropstones were among the 1st clues that something strange once happened on Earth. Drop stones are rocks that land on the seabed. It may sometimes land with so much force that the sediment deforms. In these rocks, there shouldn’t have been any dropstones. Glaciers are the most common source; ice sheet bellies collect rocks like ticks and then shed them when put to sea. It is evident from the bands of limestone interspersed with drop stone-bearing rocks that they were formed under hot tropical waters.
Around 650–700 million years ago, the Earth was once wholly encased in ice up to a kilometer thick. Surface temperatures everywhere were well below zero. Around that time, evidence suggests this catastrophe happened twice. The 1st burial seems to have lasted some 58 million years. Ten million years later, the 2nd snowball happened and lasted another 5–15 million years. Hundreds of millions of years later, partial glaciations would creep into the temperate zone regularly. As far as scientists know that ice would never again consume the Earth.
Cave fungi may have helped the Earth to drag out of the 2nd snowball, a study of new Chinese fossils published this January suggests. If it is thought that Earth was frozen solid, then it indicates that all the heavy ice has melted and the unburdened land rebounded. On new, backed rock, rainwater falling weathered the surface and seeped into cracks, creating caves.
Scientists have found both cave formations and pyrite-fossilized filaments that looked like fungi. There are fusing, and branching filaments, including A and H shaped structures. Tiny branch buds sometimes appear to be seeking each other out, along with hollow spheres solo or in chains both integrated into filaments and at their termini and two different gauges of fiber, implying at least two species. Internal walls called septa are lacked by the fibers, and often such tubes are divided into cells by the walls.
These exact types of characters many kinds of fungi today possess. There is no antibiotic look-alike between the curved and bent filaments. Studies of physical fungal fossil imposters show uniformly wide, while natural fungi tend to be narrower and may come in multiple sizes. The scientists said that structures like stalactites, stalagmites, grapelike botryoids coat the walls soon after the cavities formed. It is also colonized and catalyzed by fungi and other microorganisms. Modern cave formations bear similar microbe.
Modern fungi are known for the ability to mine rock and extract nutrients. Before snowball Earth, the oxygen level seems to be much lower than today. Before snowball Earth, the total of over 3.5 billion years of evolution and the most complex life appears to have been a sponge. Titanosaurs and dawn redwoods, and humongous funguses appear after snowball Earth.
Scientists have recently realized that Earth has probably gone through a 58-million-year Freeze phase. The central question is where rock records are and what else is unknown about Earth’s history and owners’ manual. The reason is the relevant rocks don’t survive or aren’t currently at the surface.