SELECT SCN_TO_TIMESTAMP (ORA_ROWSCN), ORIGINAL_NAME FROM USER_RECYCLEBIN

SQL> SELECT SCN_TO_TIMESTAMP(ORA_ROWSCN) FROM ent_user where user_id = 'TZR5457';

SCN_TO_TIMESTAMP(ORA_ROWSCN)
---------------------------------------------------------------------------
14-OCT-13 03.39.38.000000000 AM

SQL> SELECT SCN_TO_TIMESTAMP(ORA_ROWSCN), user_id FROM ent_user;
SELECT SCN_TO_TIMESTAMP(ORA_ROWSCN), user_id FROM ent_user
       *
ERROR at line 1:
ORA-08181: specified number is not a valid system change number
ORA-06512: at "SYS.SCN_TO_TIMESTAMP", line 1

SQL> select min(SCN) min_scn from sys.smon_scn_time;

   MIN_SCN
----------
3391402569

SQL> select SCN_TO_TIMESTAMP(3391402569) FROM DUAL;

SCN_TO_TIMESTAMP(3391402569)
---------------------------------------------------------------------------
09-OCT-13 12.50.51.000000000 AM

--Without going into detail on the structure of a rowid, in the exmple below, the block in which a row is located can be identified by characters 10 to 15. So we can see that we have rows located in two separate blocks.

SQL> select employee_id, ora_rowscn, rowid
  2  from employees
  3  where employee_id in (100, 101, 102, 103, 104, 198, 199, 200, 201);

EMPLOYEE_ID ORA_ROWSCN ROWID
----------- ---------- ------------------
        100    5069516 AAAR5kAAFAAAADNAAA
        101    5069516 AAAR5kAAFAAAADNAAB
        102    5069516 AAAR5kAAFAAAADNAAC
        103    5069516 AAAR5kAAFAAAADNAAD
        104    5069516 AAAR5kAAFAAAADNAAE
        198     948777 AAAR5kAAFAAAADOAAA
        199     948777 AAAR5kAAFAAAADOAAB
        200     948777 AAAR5kAAFAAAADOAAC
        201     948777 AAAR5kAAFAAAADOAAD

9 rows selected.

--Let's update just one row in the table.
SQL>
SQL> update employees
  2  set salary = salary
  3  where employee_id = 100;

1 row updated.

SQL>
SQL> commit;

Commit complete.
--Note the ora_rowscn changes for ALL of the rows in the block that holds the row that was updated.
SQL>
SQL> select employee_id, ora_rowscn, rowid
  2  from employees
  3  where employee_id in (100, 101, 102, 103, 104, 198, 199, 200, 201);

EMPLOYEE_ID ORA_ROWSCN ROWID
----------- ---------- ------------------
        100    5069623 AAAR5kAAFAAAADNAAA
        101    5069623 AAAR5kAAFAAAADNAAB
        102    5069623 AAAR5kAAFAAAADNAAC
        103    5069623 AAAR5kAAFAAAADNAAD
        104    5069623 AAAR5kAAFAAAADNAAE
        198     948777 AAAR5kAAFAAAADOAAA
        199     948777 AAAR5kAAFAAAADOAAB
        200     948777 AAAR5kAAFAAAADOAAC
        201     948777 AAAR5kAAFAAAADOAAD

9 rows selected.

--Let's update a row in the 'other' block.
SQL> update employees
  2  set salary = salary
  3  where employee_id = 201;

1 row updated.

SQL> commit;

Commit complete.
--Again, ALL rows change their ora_rowscn value.
SQL> select employee_id, ora_rowscn, rowid
  2  from employees
  3  where employee_id in (100, 101, 102, 103, 104, 198, 199, 200, 201);

EMPLOYEE_ID ORA_ROWSCN ROWID
----------- ---------- ------------------
        100    5069623 AAAR5kAAFAAAADNAAA
        101    5069623 AAAR5kAAFAAAADNAAB
        102    5069623 AAAR5kAAFAAAADNAAC
        103    5069623 AAAR5kAAFAAAADNAAD
        104    5069623 AAAR5kAAFAAAADNAAE
        198    5069639 AAAR5kAAFAAAADOAAA
        199    5069639 AAAR5kAAFAAAADOAAB
        200    5069639 AAAR5kAAFAAAADOAAC
        201    5069639 AAAR5kAAFAAAADOAAD

9 rows selected.