List of top Geology Questions asked in IIT JAM GG

Two boreholes A and B, both inclined towards 270°, penetrate a dipping coal bed at the same point and pass through it entirely in the sub-surface as shown in the figure below. The bed dips towards 270°. The thickness of the coal bed, measured along the borehole A is 10 m and along borehole B is 8 m. The angle between the two boreholes is 20°. The orthogonal thickness \( x \) of the coal bed is ........ m. (Round off to one decimal place)

A well-developed succession of laminated shale is bound by two volcanic ash beds that were precisely dated as shown in the schematic diagram given below. Assuming a constant sedimentation rate, the age of the fossiliferous limestone bed 65 m above the basal volcanic ash bed is ............ Ma. (Round off to nearest integer)

The data tabulated below are for flooding events in the last 400 years.
The probability of a large flood accompanied by a glacial lake outburst flood (GLOF) in 2025 is ........... \(\times 10^{-3}\). (Round off to one decimal place)

Year	Flood Size	Magnitude rank
1625	Large	2
1658	Large + GLOF	1
1692	Small	4
1704	Large	2
1767	Large	2
1806	Small	4
1872	Large + GLOF	1
1909	Large	2
1932	Large	2
1966	Medium	3
2023	Large + GLOF	1

A satellite launching vehicle is carrying a lander for Moon mapping.
As shown in the figure below, P is the position where the gravitational forces exerted by Earth and Moon on the vehicle balance out.
The distance \( P \) from the center of the Earth is ........... \(\times 10^5\) km. (Round off to two decimal places)

The isobaric temperature-composition (T–X) phase diagram given below shows the phase relation between components M and N. The equilibrium melting undergone by the rock R to generate the liquid of composition L is .............. % (In integer )

A magma having density of 2900 kg m\(^-3\) just reaches the surface through a two-layered crust as shown in the figure below. Assuming isostatic equilibrium, its depth of melting is .......... km. (Round off to one decimal place)

Which of the following stereographic projections represent(s) an upright plunging fold?

The shaded region (P) in the given ACF diagram represents the compositional range of mafic rocks that have undergone granulite facies metamorphism. Which of the following equilibrium mineral assemblages is/are identified in these mafic rocks?

Match the morphological features in Group I with their corresponding descriptions given in Group II.

Group I	Group II
P. Hyponome	3. Long tubular structure
Q. Myophore	4. Shaft with a head
R. Hypostome	1. A large plate
S. Myostracum	2. Irregular prismatic crystals

Match the stratigraphic units in Group I with their corresponding basins in Group II.

Group I	Group II
P. Kajrahat Limestone	1. Cuddapah
Q. Shahabad Limestone	2. Pranhita-Godavari
R. Chanda Limestone	3. Vindhyan
S. Narji Limestone	4. Bhima

Refer the dam section shown below. Which one of the following conditions represents the most stable state of the dam against rotation about its center of gravity?

The following map shows an outcrop of a coal bed that intersects the elevation contours. Which one of the following statements is CORRECT?

Match the cycles in Group I with the corresponding processes in Group II.

Group I	Group II
P. Hydrological cycle	1. Regolith formation
Q. Biogeochemical cycle	2. Ocean closure
R. Rock cycle	3. Infiltration
S. Wilson cycle	4. Denitrification

The schematic diagram given below shows textual relationship among garnet, muscovite, biotite and kyanite in a metapelite. Biotite defines S1 foliation and muscovite defines S2 and S3 foliations. S1, S2, and S3 fabrics were developed during distinct deformation events D1, D2, and D3, respectively. Which one of the following represents the pre-D3 mineral assemblage?

Pumping and extraction of groundwater from an unconfined aquifer resulted in a uniform drop of water table by 40 m over an area of 1 km². If the porosity of the aquifer is 35% and specific retention is 15%, the volume of water (in m³) pumped out from the affected area is __________ \times 10^6 m³. (In integer)

The orientations of two planar limbs of an overturned anticline are 045°/72°SE and 225°/37°SE. The interlimb angle of the fold in degrees is ........... (In integer)

A Cu deposit of 198 tons with average grade of 1.5% Cu contains 60% chalcopyrite, 30% bornite and 10% gangue. The maximum amount of Cu that can be extracted from chalcopyrite is .......... tons. (Round off to two decimal places)

The apparent dip amount of a limestone bed in the direction 010° is 30°. If the bed strikes 320°, the value of true dip amount in degrees is ............. (Round off to nearest integer)

A Rb–Sr isochron plot of cogenetic volcanic rocks yielded a slope of 0.003. The eruption age of these rocks is ............... Ma. (Round off to one decimal place)

The cation exchange equilibrium reaction between end-member components of orthopyroxene and ilmenite is given below: \[ \text{MgSiO}_3 + \text{FeTiO}_3 = \text{FeSiO}_3 + \text{MgTiO}_3 \] (Enstatite) (Fe-Ilmenite) (Ferrosilite) (Mg-Ilmenite)
Considering ideal mixing of Fe and Mg in orthopyroxene and ilmenite solid solutions, the mole fractions are \( X_{\text{Orthopyroxene}}^{\text{Mg}} = 0.60 \) and \( X_{\text{Ilmenite}}^{\text{Mg}} = 0.40 \). The equilibrium constant of the above reaction is ............. (Round off to two decimal places)

The Throw of a fault is 4 m and the Heave is 3 m. The Dip separation of the fault, in meters, is ............... (In integer)

Consider the present volume of the Earth’s continental crust as \(7.5 \times 10^{18}\) m³. If continental crust formation started 3.0 Ga ago, then the average rate of continental crustal growth is ............. km³ yr⁻¹. (Round off to one decimal place)

For a \(2/m\) pyroxene, the extinction angle between the vibration direction and crystallographic axis, X ⊥ c, is 36°. Then the angle Y ⊥ b in degrees will be ............. (In integer)

A kimberlite pipe has a bulk density of 2.5 g/cc and contains diamond of grade 100 carat/metric ton. If the pipe contains only 1-carat diamond crystals, then the number of diamond crystals per cubic meter in the pipe is .................. (In integer)

Moon is considered to have been formed due to high temperature condensation of post-collisional ejected material. Which of the following statement(s) related to its mantle composition as compared to CI carbonaceous chondrite is/are CORRECT?