Compatible data type add FK

Hi

I'm trying to create the tables below, and it's time to create the FK, I'm getting a error below. I didn't get what may be wrong and why it's not compatible data type.

CREATE TABLE t_agendamento_exames (

  cd_agendamento     NUMBER GENERATED BY DEFAULT AS IDENTITY,

  t_consulta_cd_consulta VARCHAR2(30) NOT NULL,

  t_exames_cd_exame   VARCHAR2(30) NOT NULL,

  ds_exame        VARCHAR2(250),

  obs_exames       VARCHAR2(250)

);

ALTER TABLE t_agendamento_exames ADD CONSTRAINT t_agendamento_exames_pk PRIMARY KEY ( cd_agendamento );

CREATE TABLE t_consulta (

  cd_consulta      NUMBER GENERATED BY DEFAULT AS IDENTITY,

  t_medico_cd_medico   VARCHAR2(30) NOT NULL,

  t_paciente_cd_paciente VARCHAR2(30) NOT NULL,

  hr_inicio       TIMESTAMP WITH TIME ZONE NOT NULL,

  hr_termino       TIMESTAMP WITH TIME ZONE NOT NULL,

  dt_hr_consulta     DATE NOT NULL,

  nr_consultorio     VARCHAR2(30),

  ob_observação_consulta VARCHAR2(300)

);

ALTER TABLE t_consulta ADD CONSTRAINT t_consulta_pk PRIMARY KEY ( cd_consulta );

ALTER TABLE t_agendamento_exames

  ADD CONSTRAINT t_agend_ex_t_cons_fk FOREIGN KEY ( t_consulta_cd_consulta )

    REFERENCES t_consulta ( cd_consulta );