Architecture

You only need a minimum of 55% in class 12th. Qualifying marks in NATA would be governed by the following rules. You must satisfy all three rules to qualify.
1. At least 25% must be secured in MCQ portion (30 out of 120)
2. At least 25% must be secured in drawing portion (20 out of 80)
3. Overall qualifying marks (out of 200) would be based on post-exam statistics and at the discretion of
the council.

Any student who has 50% marks and above in their 12th exams is eligible to sit for the NATA (National Aptitude Test in Architecture) exam. Student should have Mathematics or Business Mathematics or statistics as a compulsory subject during their 12th boards. Selection is done on merit basis through the NATA exams.

Check out the details below and do read the reviews:
https://www.shiksha.com/university/ansal-university-gurgaon-51864

Follow the link below for all the details:
https://www.coursesafter10th.com/diploma-courses/architectural-assistantship/

Yes, you can as in India you need to give NATA entrance exam and then after clearing the same you can take direct admission in B.Arch architectural colleges.
But remember that not all colleges accept NATA scores, so you need to choose the college which accepts NATA score with 3-year Diploma score.

Subjects in architecture are:
1) Architectural design
2) Building technology and materials
3) Basic design
4) Drawing graphics
5) History
6) Landscape
7) Working drawing
8) Climatology
9) Town planning
10) Building services
11) Quantity and survey.
A few more subjects varying from institute to institute

Hi, Geology covers the topics you are interested in. You may look for a more specialized field in your Masters such as Earth Sciences, Earth and Environmental Sciences, Environment, Earth and Ecosystem Sciences etc.