PL/SQL :: Check If Data Stored In Varchar2 Type Column Is Date Or Not

Is there a seeded function by which I can check all the rows which stored dates in varchar column.

I have a table say test (test_data varchar2(100));

Now I will insert all types of records into the table varchar,number dates and then i will write q query to etch all those records only which has dates only

INSERT INTO test(1);
INSERT INTO test('ABC');
INSERT INTO test(SYSDATE);
INSERT INTO test(TO_CHAR(SYSDATE,'DD-MON-YYYY'));
INSERT INTO test(TO_CHAR(SYSDATE,'DD-MON-YYYY HH24:MI:SS'));
INSERT INTO test('15/01/2012');
...
commit;