Base your answers to questions 8 on the map below, which shows Earth’s Southern Hemisphere and the inferred tectonic movement of the continent of Australia over geologic time. The arrows between the dots show the relative movement of the center of the continent of Australia. The parallels of latitude from 0° to 90° south are labeled.

8. Describe one characteristic a fossil must have in order to be considered a good index fossil.

Correct Answer:

Index fossils are fossils used to define and identify geologic periods and the age of bed rocks. Index fossils are considered reliable and good for the identification of age of bed rocks if:

• The fossils have a widespread geographic distribution, to ensure accuracy of the information.
• The fossils have short existence in a specific geologic time ensuring clarity on the time period of the fossil and the bed rock.

Base your answers to questions 11 on the map below, which shows the different lobes (sections) of the Laurentide Ice Sheet, the last continental ice sheet that covered most of New York State. The arrows show the direction that the ice lobes flowed. The terminal moraine shows the maximum advance of this ice sheet.

11. During which geologic epoch did the Laurentide Ice Sheet advance over New York State?

Correct Answer: Pleistocene Epoch

The Pleistocene has been dated from 2.588 million (±5?000 years) to 11?550 years before present (BP), with the end date expressed in radiocarbon years as 10?000 carbon-14 years BP.The modern continents were essentially at their present positions during the Pleistocene, the plates upon which they sit probably having moved no more than 100 km relative to each other since the beginning of the period.

The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, and the Ruwenzori Range in east and central Africa were larger. Glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains.

In the northern hemisphere, many glaciers fused into one. The Cordilleran ice sheet covered the North American northwest; the east was covered by the Laurentide. The Fenno-Scandian ice sheet rested on north Europe, including Great Britain; the Alpine ice sheet on the Alps. Scattered domes stretched across Siberia and the Arctic shelf. The northern seas were frozen.

The Laurentide Ice Sheet was a massive sheet of ice that covered hundreds of thousands of square miles, including most of Canada and a large portion of the northern United States, between c. 95,000 and c. 20,000 years before the present day. Its southern margin included the modern sites of New York City and Chicago, and then followed quite precisely the present course of the Missouri River up to the northern slopes of the Cypress Hills, beyond which it merged with the Cordilleran Ice Sheet.

24. During the Permian Period, sedimentary bedrock in the Appalachian Region was subjected to high temperature and pressure. Calcite deposits that had existed in this environment would most likely have formed:

A) Schist

B) Marble

C) Gabbro

D) Gneiss

Correct Answer: Option B – Marble

The Permian is a geologic period and system characterized by widespread, diverse and maturing lifeforms which comes just after the Carboniferous and that extends from 299.0 ± 0.8 to 251.0 ± 0.4 Ma (million years before the present).Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO₃). The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 470°C, and vaterite is even less stable. Calcite is the primary mineral in metamorphic marble. It also occurs as a vein mineral in deposits from hot springs, and it occurs in caverns as stalactites and stalagmites. Marble is a metamorphic rock resulting from regional or rarely contact metamorphism of sedimentary carbonate rocks, either limestone or dolomite rock, or metamorphism of older marble. This metamorphic process causes a complete recrystallization of the original rock into an interlocking mosaic of calcite, aragonite and/or dolomite crystals. The temperatures and pressures necessary to form marble usually destroy any fossils and sedimentary textures present in the original rock.

Hence, options A, C and D are incorrect.

26. One reason Tetragraptus is considered a good index fossil is that:

A) It existed during a large part of the Paleozoic Era

B) It has no living relatives found on Earth today

C) It existed over a wide geographic area

D) It has been found in New York State

Correct Answer: Option C - It existed over a wide geographic area

Tetragraptus is a genus of extinct graptolites (colonial animals related to the chordates) that occur as fossils in marine rocks of the Early Ordovician Epoch (505 to 478 million years ago). The genus is a useful guide, or index, fossil for the Early Ordovician; long-distance correlations between rock units are possible employing the many known Tetragraptus species. As its name implies, Tetragraptus is distinguished by its four branches, which are suspended from a thin filamentous support.

Hence, options A, B and D are incorrect.