Locality: Promontory Butte, Arizona, US Clastic Sedimentary Rock. Because shale consists of particles (silt and clay) that accumulate in very low energy environments, it can yield fossils of very delicate organisms.
I picked up a couple of pieces of intriguing rock in a market in Sydney a few years ago, and finally got around to looking it up. Made up of fine grained silt sized particles, it displays a quite astonishing variety of patterns all picked out in red banding on a creamy tan background. It turns out to come from the Kimberleys in Western Australia, where it outcrops in lenses in the Johnny Cake Shale member of the late Precambrian Randford Formation (what a great name), a succession of brown shales that settled, maybe seasonally, in a quiet body of water.
What happens when you have an extra detrital U-Pb age in your total detrital grain count from all samples compared to the total count you made last semester? Go through 2000 U-Pb grains to find out where it came from.
Problem solved. All graphs/figures/text fixed. 3 hours later. No progress made on the work I wanted to get done today. EXHAUSTED. that was the mental game from hell.
Baleen and sperm whales, known collectively as the great whales, include the largest animals in the history of life on Earth. With high metabolic demands and large populations, whales probably had a strong influence on marine ecosystems before the advent of industrial whaling: as consumers of fish and invertebrates; as prey to other large-bodied predators; as reservoirs and vertical and horizontal vectors for nutrients; and as detrital sources of energy and habitat in the deep sea. The decline in great whale numbers, estimated to be at least 66% and perhaps as high as 90%, has likely altered the structure and function of the oceans, but recovery is possible and in many cases is already underway.
Future changes in the structure and function of the world’s oceans can be expected with the restoration of great whale populations. Marine biologists are hoping that the recovery in whale numbers may well help to offset the effect of “destabilising stresses” on the ocean, including rising temperatures and acidification occurring as a result of climate change.
IN A NUTSHELL
Commercial whaling dramatically reduced the biomass and abundance of great whales and, until recently, we have lacked the ability to study and directly observe the functional roles of whales in marine ecosystems
Whales facilitate the transfer of nutrients by releasing fecal plumes near the surface after feeding at depth and by moving nutrients from highly productive, high-latitude feeding areas to low-latitude calving areas
Whale carcasses sequester carbon to the deep sea, where they provide habitat and food for many endemic invertebrates
The continued recovery of great whales may help to buffer marine ecosystems from destabilizing stresses and could lead to higher rates of productivity in locations where whales aggregate to feed and give birth
This small set of unassuming hills in the desert of Western Australia is known as the Jack Hills. From photos like this, it doesn’t seem particularly interesting. The Jack hills are a 2 to 3 kilometer section of a longer ridge of ancient, metamorphic rocks, folded and bent sometime in the past. The protoliths of the jack hills are sedimentary; there are conglomerates, quartz-rich layers that likely were once sandstones, banded iron formations, and chert layers, all indicating deposition in a near-shore environment such as an alluvial fan or a river delta.
“Głazy Krasnoludków” (Gorzeszowskie Skałki) - The Dwarfs’ Boulders nature reserve in Lower Silesian voivodeship, Poland. Sources of pictures: [1,2,3,4,5]
The Gorzeszów Rocks, also known as the Dwarfs’ Boulders, is a fascinating location situated close to the Krzeszów and Chełmsk Śląski towns. Protected as a natural reserve, the site represents bedrock exposures, part of shallow-water sediments of the platform cover deposited at that time in different parts of the Sudetes. The rocks form a sandstone wall of dimensions about 1100 meters long (but the width of the most interesting exposures pictured above does not exceed 200 m) and up to 30 metres high. On the top and in gapes in the wall rocky hammers, pulpits and mushrooms are exposured. Forming of these rocks occured in the Cenomanian epoch when the area was covered by a sea and during the uplifting movements these islands were strongly eroded and large amounts of detrital material. Some fossils that occur in southern parts of these rocks point a link to the Tethys Ocean, while on the north part fossilized fauna characteristic for the colder Atlantic was discovered. Waters shed by both transgressions entering the bay through a narrow strait and underwent permanent mixing. [read more - PDF]