Science Text Books
When I started out to prepare a science curriculum, I read through the NSW Board of Studies Science syllabus. Unfortunately, I did not find this particularly helpful as the document follows the current trend to specify everything in terms of 'outcomes'. This is all very nice if you know what you want to teach, because you can wrap just about anything up in the outcomes specified. It is not so helpful, however, if you are seeking guidance on actual curriculum content.
In the end, I resorted to the text book that I used some 40 years ago, Harry Messel's 'Blue Book', "Science for High School Students" (out of print). This book was published by the Science Foundation for Physics, out of the University of Sydney to support the 'new' method of teaching science that was introduced with the Wyndham Scheme. I used the Revised Edition, Second impression, dated March 1971. Unlike the original edition, the revised edition contains section summaries at the end of each chapter, which helped in building a course outline. I then used the texts listed below to flesh out my course content with more up to date material.
General Science
Ultimate Visual Dictionary of Science, Maiklem, L. (Ed.) (Dorling Kindersley, 2000) [ISBN 1-86466-162-3]
Biology
Biology (7th Ed., Australian Version), Campbell, N. A., Reece, J. B. and Myers, N.. (Pearson Education Australia, 2006) [ISBN 1-74103-386-1]
Human Anatomy (6th Ed), Martini, F. H., Timmons, M. J. and Tallitsch, R. B. (Benjamin Cummings, 2008) [ISBN 0-3215-0042-3]
I used Campbell Biology as my primary biology text. It's way beyond what could reasonably be expected from a high school student, but there is a good introduction to each subject element and plenty of material for the student who wants to read further.
Chemistry
Introductory Chemistry—A Foundation (6th Ed), Zumdahl, S.S. and DeCoste, D.J. (Houghton Mifflin, 2009) [ISBN 13: 978-0-618-80327-9]
Chemistry (7th Ed), Zumdahl, S.S. and Zumdahl, S.A. (Houghton Mifflin, 2009) [ISBN 0-618-52844-X]
Introductory Chemistry was my main resource for Chemistry. Steven Zumdahl is a prolific writer of chemistry texts, and I have several of his editions. The text coauthored by Donald DeCoste, however, I think provides a particularly good introduction that can be managed by junior high school students, even though it is a prescribed university text.
Geology and Physical Geography
Earth: An Introduction to Physical Geology (8th Ed), Tarbuck, E.J. and Lutgens, F.K. (Pearson Prentice Hall, 2005) [ISBN 0-13-114865-6]
Essentials of Geology (6th Ed), Lutgens, F.K. and Tarbuck, E.J. (Prentice Hall, 1998) [ISBN 0-13-752510-9]
Laboratory Manual in Physical Geology (7th Ed), Busch, R.M. Ed. (Pearson Prentice Hall, 2006) [ISBN 0-13-149745-6]
Fredrick Lutgens, Edward Tarbuck and Dennis Tasa are also a prolific team in the field of geology and physical geography—the illustrations by Dennis Tasa, in particular, are excellent. I used several of their books to extract the small amount of physical geography that we managed to cover, and found Tasa's illustrations on many Web sites. While there is a huge range of books from these authors, the content in many is very similar, presented in different ways for different audiences. Essentials of Geology provided material at a good level, and Earth: An Introduction to Physical Geography provided some additional detail. Both of these books are updated frequently, so if you purchase either of them, check that you're getting the latest edition (or a good discount). I purchased the Laboratory Manual for the latter text, but didn't actually use it, so I can't really comment on its value.
Physics
Holt Physics, Serway, R.A. and Faughn, J.S. (Holt, Rinehart and Winston, 2000) [ISBN 0-03-056544-8]
Conceptual Physics Fundamentals, Hewitt, P.G. (Pearson Addison Wesley, 2009) [ISBN 0-321-50136-5]
Holt Physics was my primary source for physics. This text includes detailed descriptions of many experiments and also comes with free access to additional on-line resources. The associated Problem Workbook, Lab Activities and Lab Experiments are all useful additional resources.